Bump version to 1.5.2

This specifies the maximum number of trades to be used when calculating the price. Default: 10

pom.xml

@@ -3,12 +3,12 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>org.qortal</groupId>
 	<artifactId>qortal</artifactId>
-	<version>1.4.6</version>
+	<version>1.5.2</version>
 	<packaging>jar</packaging>
 	<properties>
 		<skipTests>true</skipTests>
 		<altcoinj.version>bf9fb80</altcoinj.version>
-		<bitcoinj.version>0.15.6</bitcoinj.version>
+		<bitcoinj.version>0.15.10</bitcoinj.version>
 		<bouncycastle.version>1.64</bouncycastle.version>
 		<build.timestamp>${maven.build.timestamp}</build.timestamp>
 		<ciyam-at.version>1.3.8</ciyam-at.version>
@@ -439,6 +439,11 @@
 			<artifactId>json-simple</artifactId>
 			<version>1.1.1</version>
 		</dependency>
+		<dependency>
+			<groupId>org.json</groupId>
+			<artifactId>json</artifactId>
+			<version>20210307</version>
+		</dependency>
 		<dependency>
 			<groupId>org.apache.commons</groupId>
 			<artifactId>commons-text</artifactId>

src/main/java/org/qortal/api/model/BlockMintingInfo.java

@@ -0,0 +1,23 @@
+package org.qortal.api.model;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class BlockMintingInfo {
+
+	public byte[] minterPublicKey;
+	public int minterLevel;
+	public int onlineAccountsCount;
+	public BigDecimal maxDistance;
+	public BigInteger keyDistance;
+	public double keyDistanceRatio;
+	public long timestamp;
+	public long timeDelta;
+
+	public BlockMintingInfo() {
+	}
+
+}

src/main/java/org/qortal/api/resource/AdminResource.java

@@ -542,19 +542,8 @@ public class AdminResource {
 		Security.checkApiCallAllowed(request);
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
-			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();
-
-			blockchainLock.lockInterruptibly();
-
-			try {
-				repository.exportNodeLocalData();
-				return "true";
-			} finally {
-				blockchainLock.unlock();
-			}
-		} catch (InterruptedException e) {
-			// We couldn't lock blockchain to perform export
-			return "false";
+			repository.exportNodeLocalData();
+			return "true";
 		} catch (DataException e) {
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
 		}
@@ -564,7 +553,7 @@ public class AdminResource {
 	@Path("/repository/data")
 	@Operation(
 		summary = "Import data into repository.",
-		description = "Imports data from file on local machine. Filename is forced to 'import.script' if apiKey is not set.",
+		description = "Imports data from file on local machine. Filename is forced to 'import.json' if apiKey is not set.",
 		requestBody = @RequestBody(
 			required = true,
 			content = @Content(
@@ -588,7 +577,7 @@ public class AdminResource {
 
 		// Hard-coded because it's too dangerous to allow user-supplied filenames in weaker security contexts
 		if (Settings.getInstance().getApiKey() == null)
-			filename = "import.script";
+			filename = "import.json";
 
 		try (final Repository repository = RepositoryManager.getRepository()) {
 			ReentrantLock blockchainLock = Controller.getInstance().getBlockchainLock();

src/main/java/org/qortal/api/resource/BlocksResource.java

@@ -8,6 +8,9 @@ import io.swagger.v3.oas.annotations.media.Schema;
 import io.swagger.v3.oas.annotations.responses.ApiResponse;
 import io.swagger.v3.oas.annotations.tags.Tag;
 
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.math.RoundingMode;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -20,10 +23,13 @@ import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.Context;
 import javax.ws.rs.core.MediaType;
 
+import org.qortal.account.Account;
 import org.qortal.api.ApiError;
 import org.qortal.api.ApiErrors;
 import org.qortal.api.ApiExceptionFactory;
+import org.qortal.api.model.BlockMintingInfo;
 import org.qortal.api.model.BlockSignerSummary;
+import org.qortal.block.Block;
 import org.qortal.crypto.Crypto;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.block.BlockData;
@@ -328,6 +334,59 @@ public class BlocksResource {
 		}
 	}
 
+	@GET
+	@Path("/byheight/{height}/mintinginfo")
+	@Operation(
+			summary = "Fetch block minter info using block height",
+			description = "Returns the minter info for the block with given height",
+			responses = {
+					@ApiResponse(
+							description = "the block",
+							content = @Content(
+									schema = @Schema(
+											implementation = BlockData.class
+									)
+							)
+					)
+			}
+	)
+	@ApiErrors({
+			ApiError.BLOCK_UNKNOWN, ApiError.REPOSITORY_ISSUE
+	})
+	public BlockMintingInfo getBlockMintingInfoByHeight(@PathParam("height") int height) {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			BlockData blockData = repository.getBlockRepository().fromHeight(height);
+			if (blockData == null)
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.BLOCK_UNKNOWN);
+
+			Block block = new Block(repository, blockData);
+			BlockData parentBlockData = repository.getBlockRepository().fromSignature(blockData.getReference());
+			int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, blockData.getMinterPublicKey());
+			if (minterLevel == 0)
+				// This may be unavailable when requesting a trimmed block
+				throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_DATA);
+
+			BigInteger distance = block.calcKeyDistance(parentBlockData.getHeight(), parentBlockData.getSignature(), blockData.getMinterPublicKey(), minterLevel);
+			double ratio = new BigDecimal(distance).divide(new BigDecimal(block.MAX_DISTANCE), 40, RoundingMode.DOWN).doubleValue();
+			long timestamp = block.calcTimestamp(parentBlockData, blockData.getMinterPublicKey(), minterLevel);
+			long timeDelta = timestamp - parentBlockData.getTimestamp();
+
+			BlockMintingInfo blockMintingInfo = new BlockMintingInfo();
+			blockMintingInfo.minterPublicKey = blockData.getMinterPublicKey();
+			blockMintingInfo.minterLevel = minterLevel;
+			blockMintingInfo.onlineAccountsCount = blockData.getOnlineAccountsCount();
+			blockMintingInfo.maxDistance = new BigDecimal(block.MAX_DISTANCE);
+			blockMintingInfo.keyDistance = distance;
+			blockMintingInfo.keyDistanceRatio = ratio;
+			blockMintingInfo.timestamp = timestamp;
+			blockMintingInfo.timeDelta = timeDelta;
+
+			return blockMintingInfo;
+		} catch (DataException e) {
+			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.REPOSITORY_ISSUE, e);
+		}
+	}
+
 	@GET
 	@Path("/timestamp/{timestamp}")
 	@Operation(

src/main/java/org/qortal/api/resource/CrossChainResource.java

@@ -255,13 +255,19 @@ public class CrossChainResource {
 					description = "foreign blockchain",
 					example = "LITECOIN",
 					schema = @Schema(implementation = SupportedBlockchain.class)
-				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain) {
+				) @PathParam("blockchain") SupportedBlockchain foreignBlockchain,
+			@Parameter(
+					description = "Maximum number of trades to include in price calculation",
+					example = "10",
+					schema = @Schema(type = "integer", defaultValue = "10")
+			) @QueryParam("maxtrades") Integer maxtrades) {
 		// foreignBlockchain is required
 		if (foreignBlockchain == null)
 			throw ApiExceptionFactory.INSTANCE.createException(request, ApiError.INVALID_CRITERIA);
 
 		// We want both a minimum of 5 trades and enough trades to span at least 4 hours
 		int minimumCount = 5;
+		int maximumCount = maxtrades != null ? maxtrades : 10;
 		long minimumPeriod = 4 * 60 * 60 * 1000L; // ms
 		Boolean isFinished = Boolean.TRUE;
 
@@ -276,7 +282,7 @@ public class CrossChainResource {
 				ACCT acct = acctInfo.getValue().get();
 
 				List<ATStateData> atStates = repository.getATRepository().getMatchingFinalATStatesQuorum(codeHash,
-						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, minimumPeriod);
+						isFinished, acct.getModeByteOffset(), (long) AcctMode.REDEEMED.value, minimumCount, maximumCount, minimumPeriod);
 
 				for (ATStateData atState : atStates) {
 					CrossChainTradeData crossChainTradeData = acct.populateTradeData(repository, atState);

src/main/java/org/qortal/api/resource/PeersResource.java

@@ -321,7 +321,7 @@ public class PeersResource {
 				boolean force = true;
 				List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
 
-				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries);
+				SynchronizationResult findCommonBlockResult = Synchronizer.getInstance().fetchSummariesFromCommonBlock(repository, targetPeer, ourInitialHeight, force, peerBlockSummaries, true);
 				if (findCommonBlockResult != SynchronizationResult.OK)
 					return null;
 

src/main/java/org/qortal/block/Block.java

@@ -176,19 +176,26 @@ public class Block {
 		 * 
 		 *  @return account-level share "bin" from blockchain config, or null if founder / none found
 		 */
-		public AccountLevelShareBin getShareBin() {
+		public AccountLevelShareBin getShareBin(int blockHeight) {
 			if (this.isMinterFounder)
 				return null;
 
 			final int accountLevel = this.mintingAccountData.getLevel();
 			if (accountLevel <= 0)
-					return null;
+				return null; // level 0 isn't included in any share bins
 
-			final AccountLevelShareBin[] shareBinsByLevel = BlockChain.getInstance().getShareBinsByAccountLevel();
+			final BlockChain blockChain = BlockChain.getInstance();
+			final AccountLevelShareBin[] shareBinsByLevel = blockChain.getShareBinsByAccountLevel();
 			if (accountLevel > shareBinsByLevel.length)
 				return null;
 
-			return shareBinsByLevel[accountLevel];
+			if (blockHeight < blockChain.getShareBinFixHeight())
+				// Off-by-one bug still in effect
+				return shareBinsByLevel[accountLevel];
+
+			// level 1 stored at index 0, level 2 stored at index 1, etc.
+			return shareBinsByLevel[accountLevel-1];
+
 		}
 
 		public long distribute(long accountAmount, Map<String, Long> balanceChanges) {
@@ -225,7 +232,7 @@ public class Block {
 
 	// Other useful constants
 
-	private static final BigInteger MAX_DISTANCE;
+	public static final BigInteger MAX_DISTANCE;
 	static {
 		byte[] maxValue = new byte[Transformer.PUBLIC_KEY_LENGTH];
 		Arrays.fill(maxValue, (byte) 0xFF);
@@ -789,7 +796,9 @@ public class Block {
 		NumberFormat formatter = new DecimalFormat("0.###E0");
 		boolean isLogging = LOGGER.getLevel().isLessSpecificThan(Level.TRACE);
 
+		int blockCount = 0;
 		for (BlockSummaryData blockSummaryData : blockSummaries) {
+			blockCount++;
 			StringBuilder stringBuilder = isLogging ? new StringBuilder(512) : null;
 
 			if (isLogging)
@@ -818,11 +827,11 @@ public class Block {
 			parentHeight = blockSummaryData.getHeight();
 			parentBlockSignature = blockSummaryData.getSignature();
 
-			/* Potential future consensus change: only comparing the same number of blocks.
-			if (parentHeight >= maxHeight)
+			// After this timestamp, we only compare the same number of blocks
+			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp() && parentHeight >= maxHeight)
 				break;
-			*/
 		}
+		LOGGER.trace(String.format("Chain weight calculation was based on %d blocks", blockCount));
 
 		return cumulativeWeight;
 	}
@@ -1328,6 +1337,9 @@ public class Block {
 
 		// Give Controller our cached, valid online accounts data (if any) to help reduce CPU load for next block
 		Controller.getInstance().pushLatestBlocksOnlineAccounts(this.cachedValidOnlineAccounts);
+
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
 	}
 
 	protected void increaseAccountLevels() throws DataException {
@@ -1509,6 +1521,9 @@ public class Block {
 	public void orphan() throws DataException {
 		LOGGER.trace(() -> String.format("Orphaning block %d", this.blockData.getHeight()));
 
+		// Log some debugging info relating to the block weight calculation
+		this.logDebugInfo();
+
 		// Return AT fees and delete AT states from repository
 		orphanAtFeesAndStates();
 
@@ -1783,7 +1798,7 @@ public class Block {
 			// Find all accounts in share bin. getShareBin() returns null for minter accounts that are also founders, so they are effectively filtered out.
 			AccountLevelShareBin accountLevelShareBin = accountLevelShareBins.get(binIndex);
 			// Object reference compare is OK as all references are read-only from blockchain config.
-			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin() == accountLevelShareBin).collect(Collectors.toList());
+			List<ExpandedAccount> binnedAccounts = expandedAccounts.stream().filter(accountInfo -> accountInfo.getShareBin(this.blockData.getHeight()) == accountLevelShareBin).collect(Collectors.toList());
 
 			// No online accounts in this bin? Skip to next one
 			if (binnedAccounts.isEmpty())
@@ -1981,4 +1996,38 @@ public class Block {
 		this.repository.getAccountRepository().tidy();
 	}
 
+	private void logDebugInfo() {
+		try {
+			// Avoid calculations if possible. We have to check against INFO here, since Level.isMoreSpecificThan() confusingly uses <= rather than just <
+			if (LOGGER.getLevel().isMoreSpecificThan(Level.INFO))
+				return;
+
+			if (this.repository == null || this.getMinter() == null || this.getBlockData() == null)
+				return;
+
+			int minterLevel = Account.getRewardShareEffectiveMintingLevel(this.repository, this.getMinter().getPublicKey());
+
+			LOGGER.debug(String.format("======= BLOCK %d (%.8s) =======", this.getBlockData().getHeight(), Base58.encode(this.getSignature())));
+			LOGGER.debug(String.format("Timestamp: %d", this.getBlockData().getTimestamp()));
+			LOGGER.debug(String.format("Minter level: %d", minterLevel));
+			LOGGER.debug(String.format("Online accounts: %d", this.getBlockData().getOnlineAccountsCount()));
+			LOGGER.debug(String.format("AT count: %d", this.getBlockData().getATCount()));
+
+			BlockSummaryData blockSummaryData = new BlockSummaryData(this.getBlockData());
+			if (this.getParent() == null || this.getParent().getSignature() == null || blockSummaryData == null || minterLevel == 0)
+				return;
+
+			blockSummaryData.setMinterLevel(minterLevel);
+			BigInteger blockWeight = calcBlockWeight(this.getParent().getHeight(), this.getParent().getSignature(), blockSummaryData);
+			BigInteger keyDistance = calcKeyDistance(this.getParent().getHeight(), this.getParent().getSignature(), blockSummaryData.getMinterPublicKey(), blockSummaryData.getMinterLevel());
+			NumberFormat formatter = new DecimalFormat("0.###E0");
+
+			LOGGER.debug(String.format("Key distance: %s", formatter.format(keyDistance)));
+			LOGGER.debug(String.format("Weight: %s", formatter.format(blockWeight)));
+
+		} catch (DataException e) {
+			LOGGER.info(() -> String.format("Unable to log block debugging info: %s", e.getMessage()));
+		}
+	}
+
 }

src/main/java/org/qortal/block/BlockChain.java

@@ -71,7 +71,9 @@ public class BlockChain {
 
 	public enum FeatureTrigger {
 		atFindNextTransactionFix,
-		newBlockSigHeight;
+		newBlockSigHeight,
+		shareBinFix,
+		calcChainWeightTimestamp;
 	}
 
 	/** Map of which blockchain features are enabled when (height/timestamp) */
@@ -381,6 +383,14 @@ public class BlockChain {
 		return this.featureTriggers.get(FeatureTrigger.newBlockSigHeight.name()).intValue();
 	}
 
+	public int getShareBinFixHeight() {
+		return this.featureTriggers.get(FeatureTrigger.shareBinFix.name()).intValue();
+	}
+
+	public long getCalcChainWeightTimestamp() {
+		return this.featureTriggers.get(FeatureTrigger.calcChainWeightTimestamp.name()).longValue();
+	}
+
 	// More complex getters for aspects that change by height or timestamp
 
 	public long getRewardAtHeight(int ourHeight) {

src/main/java/org/qortal/controller/BlockMinter.java

@@ -135,16 +135,19 @@ public class BlockMinter extends Thread {
 				// Disregard peers that have "misbehaved" recently
 				peers.removeIf(Controller.hasMisbehaved);
 
-				// Disregard peers that don't have a recent block
-				peers.removeIf(Controller.hasNoRecentBlock);
+				// Disregard peers that don't have a recent block, but only if we're not in recovery mode.
+				// In that mode, we want to allow minting on top of older blocks, to recover stalled networks.
+				if (Controller.getInstance().getRecoveryMode() == false)
+					peers.removeIf(Controller.hasNoRecentBlock);
 
 				// Don't mint if we don't have enough up-to-date peers as where would the transactions/consensus come from?
 				if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 					continue;
 
-				// If our latest block isn't recent then we need to synchronize instead of minting.
+				// If our latest block isn't recent then we need to synchronize instead of minting, unless we're in recovery mode.
 				if (!peers.isEmpty() && lastBlockData.getTimestamp() < minLatestBlockTimestamp)
-					continue;
+					if (Controller.getInstance().getRecoveryMode() == false)
+						continue;
 
 				// There are enough peers with a recent block and our latest block is recent
 				// so go ahead and mint a block if possible.
@@ -165,6 +168,14 @@ public class BlockMinter extends Thread {
 				// Do we need to build any potential new blocks?
 				List<PrivateKeyAccount> newBlocksMintingAccounts = mintingAccountsData.stream().map(accountData -> new PrivateKeyAccount(repository, accountData.getPrivateKey())).collect(Collectors.toList());
 
+				// We might need to sit the next block out, if one of our minting accounts signed the previous one
+				final byte[] previousBlockMinter = previousBlockData.getMinterPublicKey();
+				final boolean mintedLastBlock = mintingAccountsData.stream().anyMatch(mintingAccount -> Arrays.equals(mintingAccount.getPublicKey(), previousBlockMinter));
+				if (mintedLastBlock) {
+					LOGGER.trace(String.format("One of our keys signed the last block, so we won't sign the next one"));
+					continue;
+				}
+
 				for (PrivateKeyAccount mintingAccount : newBlocksMintingAccounts) {
 					// First block does the AT heavy-lifting
 					if (newBlocks.isEmpty()) {
@@ -282,15 +293,17 @@ public class BlockMinter extends Thread {
 						RewardShareData rewardShareData = repository.getAccountRepository().getRewardShare(newBlock.getBlockData().getMinterPublicKey());
 
 						if (rewardShareData != null) {
-							LOGGER.info(String.format("Minted block %d, sig %.8s by %s on behalf of %s",
+							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s on behalf of %s",
 									newBlock.getBlockData().getHeight(),
 									Base58.encode(newBlock.getBlockData().getSignature()),
+									Base58.encode(newBlock.getParent().getSignature()),
 									rewardShareData.getMinter(),
 									rewardShareData.getRecipient()));
 						} else {
-							LOGGER.info(String.format("Minted block %d, sig %.8s by %s",
+							LOGGER.info(String.format("Minted block %d, sig %.8s, parent sig: %.8s by %s",
 									newBlock.getBlockData().getHeight(),
 									Base58.encode(newBlock.getBlockData().getSignature()),
+									Base58.encode(newBlock.getParent().getSignature()),
 									newBlock.getMinter().getAddress()));
 						}
 

src/main/java/org/qortal/controller/Controller.java

@@ -121,6 +121,7 @@ public class Controller extends Thread {
 	private static final long NTP_PRE_SYNC_CHECK_PERIOD = 5 * 1000L; // ms
 	private static final long NTP_POST_SYNC_CHECK_PERIOD = 5 * 60 * 1000L; // ms
 	private static final long DELETE_EXPIRED_INTERVAL = 5 * 60 * 1000L; // ms
+	private static final long RECOVERY_MODE_TIMEOUT = 10 * 60 * 1000L; // ms
 
 	// To do with online accounts list
 	private static final long ONLINE_ACCOUNTS_TASKS_INTERVAL = 10 * 1000L; // ms
@@ -175,6 +176,11 @@ public class Controller extends Thread {
 	/** Latest block signatures from other peers that we know are on inferior chains. */
 	List<ByteArray> inferiorChainSignatures = new ArrayList<>();
 
+	/** Recovery mode, which is used to bring back a stalled network */
+	private boolean recoveryMode = false;
+	private boolean peersAvailable = true; // peersAvailable must default to true
+	private long timePeersLastAvailable = 0;
+
 	/**
 	 * Map of recent requests for ARBITRARY transaction data payloads.
 	 * <p>
@@ -358,6 +364,10 @@ public class Controller extends Thread {
 		}
 	}
 
+	public boolean getRecoveryMode() {
+		return this.recoveryMode;
+	}
+
 	// Entry point
 
 	public static void main(String[] args) {
@@ -613,6 +623,11 @@ public class Controller extends Thread {
 		return peerChainTipData == null || peerChainTipData.getLastBlockSignature() == null || inferiorChainTips.contains(new ByteArray(peerChainTipData.getLastBlockSignature()));
 	};
 
+	public static final Predicate<Peer> hasOldVersion = peer -> {
+		final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
+		return peer.isAtLeastVersion(minPeerVersion) == false;
+	};
+
 	private void potentiallySynchronize() throws InterruptedException {
 		// Already synchronizing via another thread?
 		if (this.isSynchronizing)
@@ -629,6 +644,17 @@ public class Controller extends Thread {
 		// Disregard peers that don't have a recent block
 		peers.removeIf(hasNoRecentBlock);
 
+		// Disregard peers that are on an old version
+		peers.removeIf(hasOldVersion);
+
+		checkRecoveryModeForPeers(peers);
+		if (recoveryMode) {
+			peers = Network.getInstance().getHandshakedPeers();
+			peers.removeIf(hasOnlyGenesisBlock);
+			peers.removeIf(hasMisbehaved);
+			peers.removeIf(hasOldVersion);
+		}
+
 		// Check we have enough peers to potentially synchronize
 		if (peers.size() < Settings.getInstance().getMinBlockchainPeers())
 			return;
@@ -639,9 +665,31 @@ public class Controller extends Thread {
 		// Disregard peers that are on the same block as last sync attempt and we didn't like their chain
 		peers.removeIf(hasInferiorChainTip);
 
+		final int peersBeforeComparison = peers.size();
+
+		// Request recent block summaries from the remaining peers, and locate our common block with each
+		Synchronizer.getInstance().findCommonBlocksWithPeers(peers);
+
+		// Compare the peers against each other, and against our chain, which will return an updated list excluding those without common blocks
+		peers = Synchronizer.getInstance().comparePeers(peers);
+
+		// We may have added more inferior chain tips when comparing peers, so remove any peers that are currently on those chains
+		peers.removeIf(hasInferiorChainTip);
+
+		final int peersRemoved = peersBeforeComparison - peers.size();
+		if (peersRemoved > 0 && peers.size() > 0)
+			LOGGER.info(String.format("Ignoring %d peers on inferior chains. Peers remaining: %d", peersRemoved, peers.size()));
+
 		if (peers.isEmpty())
 			return;
 
+		if (peers.size() > 1) {
+			StringBuilder finalPeersString = new StringBuilder();
+			for (Peer peer : peers)
+				finalPeersString = finalPeersString.length() > 0 ? finalPeersString.append(", ").append(peer) : finalPeersString.append(peer);
+			LOGGER.info(String.format("Choosing random peer from: [%s]", finalPeersString.toString()));
+		}
+
 		// Pick random peer to sync with
 		int index = new SecureRandom().nextInt(peers.size());
 		Peer peer = peers.get(index);
@@ -744,6 +792,46 @@ public class Controller extends Thread {
 		}
 	}
 
+	private boolean checkRecoveryModeForPeers(List<Peer> qualifiedPeers) {
+		List<Peer> handshakedPeers = Network.getInstance().getHandshakedPeers();
+
+		if (handshakedPeers.size() > 0) {
+			// There is at least one handshaked peer
+			if (qualifiedPeers.isEmpty()) {
+				// There are no 'qualified' peers - i.e. peers that have a recent block we can sync to
+				boolean werePeersAvailable = peersAvailable;
+				peersAvailable = false;
+
+				// If peers only just became unavailable, update our record of the time they were last available
+				if (werePeersAvailable)
+					timePeersLastAvailable = NTP.getTime();
+
+				// If enough time has passed, enter recovery mode, which lifts some restrictions on who we can sync with and when we can mint
+				if (NTP.getTime() - timePeersLastAvailable > RECOVERY_MODE_TIMEOUT) {
+					if (recoveryMode == false) {
+						LOGGER.info(String.format("Peers have been unavailable for %d minutes. Entering recovery mode...", RECOVERY_MODE_TIMEOUT/60/1000));
+						recoveryMode = true;
+					}
+				}
+			} else {
+				// We now have at least one peer with a recent block, so we can exit recovery mode and sync normally
+				peersAvailable = true;
+				if (recoveryMode) {
+					LOGGER.info("Peers have become available again. Exiting recovery mode...");
+					recoveryMode = false;
+				}
+			}
+		}
+		return recoveryMode;
+	}
+
+	public void addInferiorChainSignature(byte[] inferiorSignature) {
+		// Update our list of inferior chain tips
+		ByteArray inferiorChainSignature = new ByteArray(inferiorSignature);
+		if (!inferiorChainSignatures.contains(inferiorChainSignature))
+			inferiorChainSignatures.add(inferiorChainSignature);
+	}
+
 	public static class StatusChangeEvent implements Event {
 		public StatusChangeEvent() {
 		}
@@ -775,7 +863,7 @@ public class Controller extends Thread {
 				actionText = Translator.INSTANCE.translate("SysTray", "MINTING_DISABLED");
 		}
 
-		String tooltip = String.format("%s - %d %s - %s %d", actionText, numberOfPeers, connectionsText, heightText, height);
+		String tooltip = String.format("%s - %d %s - %s %d", actionText, numberOfPeers, connectionsText, heightText, height) + "\n" + String.format("Build version: %s", this.buildVersion);
 		SysTray.getInstance().setToolTipText(tooltip);
 
 		this.callbackExecutor.execute(() -> {

src/main/java/org/qortal/controller/Synchronizer.java

@@ -8,6 +8,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
+import java.util.Iterator;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -15,8 +16,10 @@ import org.qortal.account.Account;
 import org.qortal.account.PublicKeyAccount;
 import org.qortal.block.Block;
 import org.qortal.block.Block.ValidationResult;
+import org.qortal.block.BlockChain;
 import org.qortal.data.block.BlockData;
 import org.qortal.data.block.BlockSummaryData;
+import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.transaction.RewardShareTransactionData;
 import org.qortal.data.transaction.TransactionData;
@@ -32,8 +35,10 @@ import org.qortal.network.message.Message.MessageType;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.repository.RepositoryManager;
+import org.qortal.settings.Settings;
 import org.qortal.transaction.Transaction;
 import org.qortal.utils.Base58;
+import org.qortal.utils.NTP;
 
 public class Synchronizer {
 
@@ -53,9 +58,6 @@ public class Synchronizer {
 	/** Maximum number of block signatures we ask from peer in one go */
 	private static final int MAXIMUM_REQUEST_SIZE = 200; // XXX move to Settings?
 
-	/** Number of retry attempts if a peer fails to respond with the requested data */
-	private static final int MAXIMUM_RETRIES = 1; // XXX move to Settings?
-
 
 	private static Synchronizer instance;
 
@@ -75,6 +77,406 @@ public class Synchronizer {
 		return instance;
 	}
 
+
+	/**
+	 * Iterate through a list of supplied peers, and attempt to find our common block with each.
+	 * If a common block is found, its summary will be retained in the peer's commonBlockSummary property, for processing later.
+	 * <p>
+	 * Will return <tt>SynchronizationResult.OK</tt> on success.
+	 * <p>
+	 * @param peers
+	 * @return SynchronizationResult.OK if the process completed successfully, or a different SynchronizationResult if something went wrong.
+	 * @throws InterruptedException
+	 */
+	public SynchronizationResult findCommonBlocksWithPeers(List<Peer> peers) throws InterruptedException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			try {
+
+				if (peers.size() == 0)
+					return SynchronizationResult.NOTHING_TO_DO;
+
+				// If our latest block is very old, it's best that we don't try and determine the best peers to sync to.
+				// This is because it can involve very large chain comparisons, which is too intensive.
+				// In reality, most forking problems occur near the chain tips, so we will reserve this functionality for those situations.
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				if (minLatestBlockTimestamp == null)
+					return SynchronizationResult.REPOSITORY_ISSUE;
+
+				final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+				if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+					LOGGER.debug(String.format("Our latest block is very old, so we won't collect common block info from peers"));
+					return SynchronizationResult.NOTHING_TO_DO;
+				}
+
+				LOGGER.debug(String.format("Searching for common blocks with %d peers...", peers.size()));
+				final long startTime = System.currentTimeMillis();
+				int commonBlocksFound = 0;
+				boolean wereNewRequestsMade = false;
+
+				for (Peer peer : peers) {
+					// Are we shutting down?
+					if (Controller.isStopping())
+						return SynchronizationResult.SHUTTING_DOWN;
+
+					// Check if we can use the cached common block data, by comparing the peer's current chain tip against the peer's chain tip when we last found our common block
+					if (peer.canUseCachedCommonBlockData()) {
+						LOGGER.debug(String.format("Skipping peer %s because we already have the latest common block data in our cache. Cached common block sig is %.08s", peer, Base58.encode(peer.getCommonBlockData().getCommonBlockSummary().getSignature())));
+						commonBlocksFound++;
+						continue;
+					}
+
+					// Cached data is stale, so clear it and repopulate
+					peer.setCommonBlockData(null);
+
+					// Search for the common block
+					Synchronizer.getInstance().findCommonBlockWithPeer(peer, repository);
+					if (peer.getCommonBlockData() != null)
+						commonBlocksFound++;
+
+					// This round wasn't served entirely from the cache, so we may want to log the results
+					wereNewRequestsMade = true;
+				}
+
+				if (wereNewRequestsMade) {
+					final long totalTimeTaken = System.currentTimeMillis() - startTime;
+					LOGGER.info(String.format("Finished searching for common blocks with %d peer%s. Found: %d. Total time taken: %d ms", peers.size(), (peers.size() != 1 ? "s" : ""), commonBlocksFound, totalTimeTaken));
+				}
+
+				return SynchronizationResult.OK;
+			} finally {
+				repository.discardChanges(); // Free repository locks, if any, also in case anything went wrong
+			}
+		} catch (DataException e) {
+			LOGGER.error("Repository issue during synchronization with peer", e);
+			return SynchronizationResult.REPOSITORY_ISSUE;
+		}
+	}
+
+	/**
+	 * Attempt to find the find our common block with supplied peer.
+	 * If a common block is found, its summary will be retained in the peer's commonBlockSummary property, for processing later.
+	 * <p>
+	 * Will return <tt>SynchronizationResult.OK</tt> on success.
+	 * <p>
+	 * @param peer
+	 * @param repository
+	 * @return SynchronizationResult.OK if the process completed successfully, or a different SynchronizationResult if something went wrong.
+	 * @throws InterruptedException
+	 */
+	public SynchronizationResult findCommonBlockWithPeer(Peer peer, Repository repository) throws InterruptedException {
+		try {
+			final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+			final int ourInitialHeight = ourLatestBlockData.getHeight();
+
+			PeerChainTipData peerChainTipData = peer.getChainTipData();
+			int peerHeight = peerChainTipData.getLastHeight();
+			byte[] peersLastBlockSignature = peerChainTipData.getLastBlockSignature();
+
+			byte[] ourLastBlockSignature = ourLatestBlockData.getSignature();
+			LOGGER.debug(String.format("Fetching summaries from peer %s at height %d, sig %.8s, ts %d; our height %d, sig %.8s, ts %d", peer,
+					peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
+					ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
+
+			List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
+			SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, false, peerBlockSummaries, false);
+			if (findCommonBlockResult != SynchronizationResult.OK) {
+				// Logging performed by fetchSummariesFromCommonBlock() above
+				peer.setCommonBlockData(null);
+				return findCommonBlockResult;
+			}
+
+			// First summary is common block
+			final BlockData commonBlockData = repository.getBlockRepository().fromSignature(peerBlockSummaries.get(0).getSignature());
+			final BlockSummaryData commonBlockSummary = new BlockSummaryData(commonBlockData);
+			final int commonBlockHeight = commonBlockData.getHeight();
+			final byte[] commonBlockSig = commonBlockData.getSignature();
+			final String commonBlockSig58 = Base58.encode(commonBlockSig);
+			LOGGER.debug(String.format("Common block with peer %s is at height %d, sig %.8s, ts %d", peer,
+					commonBlockHeight, commonBlockSig58, commonBlockData.getTimestamp()));
+			peerBlockSummaries.remove(0);
+
+			// Store the common block summary against the peer, and the current chain tip (for caching)
+			peer.setCommonBlockData(new CommonBlockData(commonBlockSummary, peerChainTipData));
+
+			return SynchronizationResult.OK;
+		} catch (DataException e) {
+			LOGGER.error("Repository issue during synchronization with peer", e);
+			return SynchronizationResult.REPOSITORY_ISSUE;
+		}
+	}
+
+
+	/**
+	 * Compare a list of peers to determine the best peer(s) to sync to next.
+	 * <p>
+	 * Will return a filtered list of peers on success, or an identical list of peers on failure.
+	 * This allows us to fall back to legacy behaviour (random selection from the entire list of peers), if we are unable to make the comparison.
+	 * <p>
+	 * @param peers
+	 * @return a list of peers, possibly filtered.
+	 * @throws InterruptedException
+	 */
+	public List<Peer> comparePeers(List<Peer> peers) throws InterruptedException {
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			try {
+
+				// If our latest block is very old, it's best that we don't try and determine the best peers to sync to.
+				// This is because it can involve very large chain comparisons, which is too intensive.
+				// In reality, most forking problems occur near the chain tips, so we will reserve this functionality for those situations.
+				final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+				if (minLatestBlockTimestamp == null)
+					return peers;
+
+				final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+				if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+					LOGGER.debug(String.format("Our latest block is very old, so we won't filter the peers list"));
+					return peers;
+				}
+
+				// We will switch to a new chain weight consensus algorithm at a hard fork, so determine if this has happened yet
+				boolean usingSameLengthChainWeight = (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp());
+				LOGGER.debug(String.format("Using %s chain weight consensus algorithm", (usingSameLengthChainWeight ? "same-length" : "variable-length")));
+
+				// Retrieve a list of unique common blocks from this list of peers
+				List<BlockSummaryData> commonBlocks = this.uniqueCommonBlocks(peers);
+
+				// Order common blocks by height, in ascending order
+				// This is essential for the logic below to make the correct decisions when discarding chains - do not remove
+				commonBlocks.sort((b1, b2) -> Integer.valueOf(b1.getHeight()).compareTo(Integer.valueOf(b2.getHeight())));
+
+				// Get our latest height
+				final int ourHeight = ourLatestBlockData.getHeight();
+
+				// Create a placeholder to track of common blocks that we can discard due to being inferior chains
+				int dropPeersAfterCommonBlockHeight = 0;
+
+				// Remove peers with no common block data
+				Iterator iterator = peers.iterator();
+				while (iterator.hasNext()) {
+					Peer peer = (Peer) iterator.next();
+					if (peer.getCommonBlockData() == null) {
+						LOGGER.debug(String.format("Removed peer %s because it has no common block data", peer));
+						iterator.remove();
+					}
+				}
+
+				// Loop through each group of common blocks
+				for (BlockSummaryData commonBlockSummary : commonBlocks) {
+					List<Peer> peersSharingCommonBlock = peers.stream().filter(peer -> peer.getCommonBlockData().getCommonBlockSummary().equals(commonBlockSummary)).collect(Collectors.toList());
+
+					// Check if we need to discard this group of peers
+					if (dropPeersAfterCommonBlockHeight > 0) {
+						if (commonBlockSummary.getHeight() > dropPeersAfterCommonBlockHeight) {
+							// We have already determined that the correct chain diverged from a lower height. We are safe to skip these peers.
+							for (Peer peer : peersSharingCommonBlock) {
+								LOGGER.debug(String.format("Peer %s has common block at height %d but the superior chain is at height %d. Removing it from this round.", peer, commonBlockSummary.getHeight(), dropPeersAfterCommonBlockHeight));
+								Controller.getInstance().addInferiorChainSignature(peer.getChainTipData().getLastBlockSignature());
+							}
+							continue;
+						}
+					}
+
+					// Calculate the length of the shortest peer chain sharing this common block, including our chain
+					final int ourAdditionalBlocksAfterCommonBlock = ourHeight - commonBlockSummary.getHeight();
+					int minChainLength = this.calculateMinChainLengthOfPeers(peersSharingCommonBlock, commonBlockSummary);
+
+					// Fetch block summaries from each peer
+					for (Peer peer : peersSharingCommonBlock) {
+
+						// If we're shutting down, just return the latest peer list
+						if (Controller.isStopping())
+							return peers;
+
+						// Count the number of blocks this peer has beyond our common block
+						final PeerChainTipData peerChainTipData = peer.getChainTipData();
+						final int peerHeight = peerChainTipData.getLastHeight();
+						final byte[] peerLastBlockSignature = peerChainTipData.getLastBlockSignature();
+						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
+						// Limit the number of blocks we are comparing. FUTURE: we could request more in batches, but there may not be a case when this is needed
+						int summariesRequired = Math.min(peerAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
+
+						// Check if we can use the cached common block summaries, by comparing the peer's current chain tip against the peer's chain tip when we last found our common block
+						boolean useCachedSummaries = false;
+						if (peer.canUseCachedCommonBlockData()) {
+							if (peer.getCommonBlockData().getBlockSummariesAfterCommonBlock() != null) {
+								if (peer.getCommonBlockData().getBlockSummariesAfterCommonBlock().size() == summariesRequired) {
+									LOGGER.trace(String.format("Using cached block summaries for peer %s", peer));
+									useCachedSummaries = true;
+								}
+							}
+						}
+
+						if (useCachedSummaries == false) {
+							if (summariesRequired > 0) {
+								LOGGER.trace(String.format("Requesting %d block summar%s from peer %s after common block %.8s. Peer height: %d", summariesRequired, (summariesRequired != 1 ? "ies" : "y"), peer, Base58.encode(commonBlockSummary.getSignature()), peerHeight));
+
+								// Forget any cached summaries
+								peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(null);
+
+								// Request new block summaries
+								List<BlockSummaryData> blockSummaries = this.getBlockSummaries(peer, commonBlockSummary.getSignature(), summariesRequired);
+								if (blockSummaries != null) {
+									LOGGER.trace(String.format("Peer %s returned %d block summar%s", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y")));
+
+									if (blockSummaries.size() < summariesRequired)
+										// This could mean that the peer has re-orged. Exclude this peer until they return the summaries we expect.
+										LOGGER.debug(String.format("Peer %s returned %d block summar%s instead of expected %d - excluding them from this round", peer, blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"), summariesRequired));
+									else if (blockSummaryWithSignature(peerLastBlockSignature, blockSummaries) == null)
+										// We don't have a block summary for the peer's reported chain tip, so should exclude it
+										LOGGER.debug(String.format("Peer %s didn't return a block summary with signature %.8s - excluding them from this round", peer, Base58.encode(peerLastBlockSignature)));
+									else
+										// All looks good, so store the retrieved block summaries in the peer's cache
+										peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(blockSummaries);
+								}
+							} else {
+								// There are no block summaries after this common block
+								peer.getCommonBlockData().setBlockSummariesAfterCommonBlock(null);
+							}
+						}
+
+						// Reduce minChainLength if needed. If we don't have any blocks, this peer will be excluded from chain weight comparisons later in the process, so we shouldn't update minChainLength
+						List <BlockSummaryData> peerBlockSummaries = peer.getCommonBlockData().getBlockSummariesAfterCommonBlock();
+						if (peerBlockSummaries != null && peerBlockSummaries.size() > 0)
+							if (peerBlockSummaries.size() < minChainLength)
+								minChainLength = peerBlockSummaries.size();
+					}
+
+					// Fetch our corresponding block summaries. Limit to MAXIMUM_REQUEST_SIZE, in order to make the comparison fairer, as peers have been limited too
+					final int ourSummariesRequired = Math.min(ourAdditionalBlocksAfterCommonBlock, MAXIMUM_REQUEST_SIZE);
+					LOGGER.trace(String.format("About to fetch our block summaries from %d to %d. Our height: %d", commonBlockSummary.getHeight() + 1, commonBlockSummary.getHeight() + ourSummariesRequired, ourHeight));
+					List<BlockSummaryData> ourBlockSummaries = repository.getBlockRepository().getBlockSummaries(commonBlockSummary.getHeight() + 1, commonBlockSummary.getHeight() + ourSummariesRequired);
+					if (ourBlockSummaries.isEmpty()) {
+						LOGGER.debug(String.format("We don't have any block summaries so can't compare our chain against peers with this common block. We can still compare them against each other."));
+					}
+					else {
+						populateBlockSummariesMinterLevels(repository, ourBlockSummaries);
+						// Reduce minChainLength if we have less summaries
+						if (ourBlockSummaries.size() < minChainLength)
+							minChainLength = ourBlockSummaries.size();
+					}
+
+					// Create array to hold peers for comparison
+					List<Peer> superiorPeersForComparison = new ArrayList<>();
+
+					// Calculate max height for chain weight comparisons
+					int maxHeightForChainWeightComparisons = commonBlockSummary.getHeight() + minChainLength;
+
+					// Calculate our chain weight
+					BigInteger ourChainWeight = BigInteger.valueOf(0);
+					if (ourBlockSummaries.size() > 0)
+						ourChainWeight = Block.calcChainWeight(commonBlockSummary.getHeight(), commonBlockSummary.getSignature(), ourBlockSummaries, maxHeightForChainWeightComparisons);
+
+					NumberFormat formatter = new DecimalFormat("0.###E0");
+					NumberFormat accurateFormatter = new DecimalFormat("0.################E0");
+					LOGGER.debug(String.format("Our chain weight based on %d blocks is %s", (usingSameLengthChainWeight ? minChainLength : ourBlockSummaries.size()), formatter.format(ourChainWeight)));
+
+					LOGGER.debug(String.format("Listing peers with common block %.8s...", Base58.encode(commonBlockSummary.getSignature())));
+					for (Peer peer : peersSharingCommonBlock) {
+						final int peerHeight = peer.getChainTipData().getLastHeight();
+						final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
+						final CommonBlockData peerCommonBlockData = peer.getCommonBlockData();
+
+						if (peerCommonBlockData == null || peerCommonBlockData.getBlockSummariesAfterCommonBlock() == null || peerCommonBlockData.getBlockSummariesAfterCommonBlock().isEmpty()) {
+							// No response - remove this peer for now
+							LOGGER.debug(String.format("Peer %s doesn't have any block summaries - removing it from this round", peer));
+							peers.remove(peer);
+							continue;
+						}
+
+						final List<BlockSummaryData> peerBlockSummariesAfterCommonBlock = peerCommonBlockData.getBlockSummariesAfterCommonBlock();
+						populateBlockSummariesMinterLevels(repository, peerBlockSummariesAfterCommonBlock);
+
+						// Calculate cumulative chain weight of this blockchain subset, from common block to highest mutual block held by all peers in this group.
+						LOGGER.debug(String.format("About to calculate chain weight based on %d blocks for peer %s with common block %.8s (peer has %d blocks after common block)", (usingSameLengthChainWeight ? minChainLength : peerBlockSummariesAfterCommonBlock.size()), peer, Base58.encode(commonBlockSummary.getSignature()), peerAdditionalBlocksAfterCommonBlock));
+						BigInteger peerChainWeight = Block.calcChainWeight(commonBlockSummary.getHeight(), commonBlockSummary.getSignature(), peerBlockSummariesAfterCommonBlock, maxHeightForChainWeightComparisons);
+						peer.getCommonBlockData().setChainWeight(peerChainWeight);
+						LOGGER.debug(String.format("Chain weight of peer %s based on %d blocks (%d - %d) is %s", peer, (usingSameLengthChainWeight ? minChainLength : peerBlockSummariesAfterCommonBlock.size()), peerBlockSummariesAfterCommonBlock.get(0).getHeight(), peerBlockSummariesAfterCommonBlock.get(peerBlockSummariesAfterCommonBlock.size()-1).getHeight(), formatter.format(peerChainWeight)));
+
+						// Compare against our chain - if our blockchain has greater weight then don't synchronize with peer (or any others in this group)
+						if (ourChainWeight.compareTo(peerChainWeight) > 0) {
+							// This peer is on an inferior chain - remove it
+							LOGGER.debug(String.format("Peer %s is on an inferior chain to us - removing it from this round", peer));
+							peers.remove(peer);
+						}
+						else {
+							// Our chain is inferior or equal
+							LOGGER.debug(String.format("Peer %s is on an equal or better chain to us. We will compare the other peers sharing this common block against each other, and drop all peers sharing higher common blocks.", peer));
+							dropPeersAfterCommonBlockHeight = commonBlockSummary.getHeight();
+							superiorPeersForComparison.add(peer);
+						}
+					}
+
+					// Now that we have selected the best peers, compare them against each other and remove any with lower weights
+					if (superiorPeersForComparison.size() > 0) {
+						BigInteger bestChainWeight = null;
+						for (Peer peer : superiorPeersForComparison) {
+							// Increase bestChainWeight if needed
+							if (bestChainWeight == null || peer.getCommonBlockData().getChainWeight().compareTo(bestChainWeight) >= 0)
+								bestChainWeight = peer.getCommonBlockData().getChainWeight();
+						}
+						for (Peer peer : superiorPeersForComparison) {
+							// Check if we should discard an inferior peer
+							if (peer.getCommonBlockData().getChainWeight().compareTo(bestChainWeight) < 0) {
+								BigInteger difference = bestChainWeight.subtract(peer.getCommonBlockData().getChainWeight());
+								LOGGER.debug(String.format("Peer %s has a lower chain weight (difference: %s) than other peer(s) in this group - removing it from this round.", peer, accurateFormatter.format(difference)));
+								peers.remove(peer);
+							}
+						}
+						// FUTURE: we may want to prefer peers with additional blocks, and compare the additional blocks against each other.
+						// This would fast track us to the best candidate for the latest block.
+						// Right now, peers with the exact same chain as us are treated equally to those with an additional block.
+					}
+				}
+
+				return peers;
+			} finally {
+				repository.discardChanges(); // Free repository locks, if any, also in case anything went wrong
+			}
+		} catch (DataException e) {
+			LOGGER.error("Repository issue during peer comparison", e);
+			return peers;
+		}
+	}
+
+	private List<BlockSummaryData> uniqueCommonBlocks(List<Peer> peers) {
+		List<BlockSummaryData> commonBlocks = new ArrayList<>();
+
+		for (Peer peer : peers) {
+			if (peer.getCommonBlockData() != null && peer.getCommonBlockData().getCommonBlockSummary() != null) {
+				LOGGER.trace(String.format("Peer %s has common block %.8s", peer, Base58.encode(peer.getCommonBlockData().getCommonBlockSummary().getSignature())));
+
+				BlockSummaryData commonBlockSummary = peer.getCommonBlockData().getCommonBlockSummary();
+				if (!commonBlocks.contains(commonBlockSummary))
+					commonBlocks.add(commonBlockSummary);
+			}
+			else {
+				LOGGER.trace(String.format("Peer %s has no common block data. Skipping...", peer));
+			}
+		}
+
+		return commonBlocks;
+	}
+
+	private int calculateMinChainLengthOfPeers(List<Peer> peersSharingCommonBlock, BlockSummaryData commonBlockSummary) {
+		// Calculate the length of the shortest peer chain sharing this common block
+		int minChainLength = 0;
+		for (Peer peer : peersSharingCommonBlock) {
+			final int peerHeight = peer.getChainTipData().getLastHeight();
+			final int peerAdditionalBlocksAfterCommonBlock = peerHeight - commonBlockSummary.getHeight();
+
+			if (peerAdditionalBlocksAfterCommonBlock < minChainLength || minChainLength == 0)
+				minChainLength = peerAdditionalBlocksAfterCommonBlock;
+		}
+		return minChainLength;
+	}
+
+	private BlockSummaryData blockSummaryWithSignature(byte[] signature, List<BlockSummaryData> blockSummaries) {
+		if (blockSummaries != null)
+			return blockSummaries.stream().filter(blockSummary -> Arrays.equals(blockSummary.getSignature(), signature)).findAny().orElse(null);
+		return null;
+	}
+
+
 	/**
 	 * Attempt to synchronize blockchain with peer.
 	 * <p>
@@ -109,10 +511,13 @@ public class Synchronizer {
 							ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
 
 					List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
-					SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries);
-					if (findCommonBlockResult != SynchronizationResult.OK)
+					SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries, true);
+					if (findCommonBlockResult != SynchronizationResult.OK) {
 						// Logging performed by fetchSummariesFromCommonBlock() above
+						// Clear our common block cache for this peer
+						peer.setCommonBlockData(null);
 						return findCommonBlockResult;
+					}
 
 					// First summary is common block
 					final BlockData commonBlockData = repository.getBlockRepository().fromSignature(peerBlockSummaries.get(0).getSignature());
@@ -188,7 +593,7 @@ public class Synchronizer {
 	 * @throws DataException
 	 * @throws InterruptedException
 	 */
-	public SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon) throws DataException, InterruptedException {
+	public SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon, boolean infoLogWhenNotFound) throws DataException, InterruptedException {
 		// Start by asking for a few recent block hashes as this will cover a majority of reorgs
 		// Failing that, back off exponentially
 		int step = INITIAL_BLOCK_STEP;
@@ -217,8 +622,12 @@ public class Synchronizer {
 			blockSummariesBatch = this.getBlockSummaries(peer, testSignature, step);
 
 			if (blockSummariesBatch == null) {
+				if (infoLogWhenNotFound)
+					LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
+				else
+					LOGGER.debug(String.format("Error while trying to find common block with peer %s", peer));
+				
 				// No response - give up this time
-				LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
 				return SynchronizationResult.NO_REPLY;
 			}
 
@@ -336,7 +745,7 @@ public class Synchronizer {
 			populateBlockSummariesMinterLevels(repository, ourBlockSummaries);
 			populateBlockSummariesMinterLevels(repository, peerBlockSummaries);
 
-			final int mutualHeight = commonBlockHeight - 1 + Math.min(ourBlockSummaries.size(), peerBlockSummaries.size());
+			final int mutualHeight = commonBlockHeight + Math.min(ourBlockSummaries.size(), peerBlockSummaries.size());
 
 			// Calculate cumulative chain weights of both blockchain subsets, from common block to highest mutual block.
 			BigInteger ourChainWeight = Block.calcChainWeight(commonBlockHeight, commonBlockSig, ourBlockSummaries, mutualHeight);
@@ -366,6 +775,7 @@ public class Synchronizer {
 
 		LOGGER.debug(() -> String.format("Fetching peer %s chain from height %d, sig %.8s", peer, commonBlockHeight, commonBlockSig58));
 
+		final int maxRetries = Settings.getInstance().getMaxRetries();
 
 		// Overall plan: fetch peer's blocks first, then orphan, then apply
 
@@ -399,11 +809,34 @@ public class Synchronizer {
                     LOGGER.info(String.format("Peer %s failed to respond with more block signatures after height %d, sig %.8s", peer,
                             height, Base58.encode(latestPeerSignature)));
 
-                    // If we have already received blocks from this peer, go ahead and apply them
+					// Clear our cache of common block summaries for this peer, as they are likely to be invalid
+					CommonBlockData cachedCommonBlockData = peer.getCommonBlockData();
+					if (cachedCommonBlockData != null)
+						cachedCommonBlockData.setBlockSummariesAfterCommonBlock(null);
+
+                    // If we have already received newer blocks from this peer that what we have already, go ahead and apply them
                     if (peerBlocks.size() > 0) {
-                        break;
+						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+                    	final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
+						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+						if (ourLatestBlockData != null && peerLatestBlock != null && minLatestBlockTimestamp != null) {
+
+							// If our latest block is very old....
+							if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+								// ... and we have received a block that is more recent than our latest block ...
+								if (peerLatestBlock.getBlockData().getTimestamp() > ourLatestBlockData.getTimestamp()) {
+									// ... then apply the blocks, as it takes us a step forward.
+									// This is particularly useful when starting up a node that was on a small fork when it was last shut down.
+									// In these cases, we now allow the node to sync forward, and get onto the main chain again.
+									// Without this, we would require that the node syncs ENTIRELY with this peer,
+									// and any problems downloading a block would cause all progress to be lost.
+									LOGGER.debug(String.format("Newly received blocks are %d ms newer than our latest block - so we will apply them", peerLatestBlock.getBlockData().getTimestamp() - ourLatestBlockData.getTimestamp()));
+									break;
+								}
+							}
+						}
                     }
-                    // Otherwise, give up and move on to the next peer
+					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated or incomplete state
                     return SynchronizationResult.NO_REPLY;
                 }
 
@@ -426,13 +859,30 @@ public class Synchronizer {
 				LOGGER.info(String.format("Peer %s failed to respond with block for height %d, sig %.8s", peer,
 						nextHeight, Base58.encode(nextPeerSignature)));
 
-				if (retryCount >= MAXIMUM_RETRIES) {
-
-					// If we have already received blocks from this peer, go ahead and apply them
+				if (retryCount >= maxRetries) {
+					// If we have already received newer blocks from this peer that what we have already, go ahead and apply them
 					if (peerBlocks.size() > 0) {
-						break;
+						final BlockData ourLatestBlockData = repository.getBlockRepository().getLastBlock();
+						final Block peerLatestBlock = peerBlocks.get(peerBlocks.size() - 1);
+						final Long minLatestBlockTimestamp = Controller.getMinimumLatestBlockTimestamp();
+						if (ourLatestBlockData != null && peerLatestBlock != null && minLatestBlockTimestamp != null) {
+
+							// If our latest block is very old....
+							if (ourLatestBlockData.getTimestamp() < minLatestBlockTimestamp) {
+								// ... and we have received a block that is more recent than our latest block ...
+								if (peerLatestBlock.getBlockData().getTimestamp() > ourLatestBlockData.getTimestamp()) {
+									// ... then apply the blocks, as it takes us a step forward.
+									// This is particularly useful when starting up a node that was on a small fork when it was last shut down.
+									// In these cases, we now allow the node to sync forward, and get onto the main chain again.
+									// Without this, we would require that the node syncs ENTIRELY with this peer,
+									// and any problems downloading a block would cause all progress to be lost.
+									LOGGER.debug(String.format("Newly received blocks are %d ms newer than our latest block - so we will apply them", peerLatestBlock.getBlockData().getTimestamp() - ourLatestBlockData.getTimestamp()));
+									break;
+								}
+							}
+						}
 					}
-					// Otherwise, give up and move on to the next peer
+					// Otherwise, give up and move on to the next peer, to avoid putting our chain into an outdated or incomplete state
 					return SynchronizationResult.NO_REPLY;
 
 				} else {
@@ -440,9 +890,9 @@ public class Synchronizer {
 					peerBlockSignatures.clear();
 					numberSignaturesRequired = peerHeight - height;
 
-					// Retry until retryCount reaches MAXIMUM_RETRIES
+					// Retry until retryCount reaches maxRetries
 					retryCount++;
-					int triesRemaining = MAXIMUM_RETRIES - retryCount;
+					int triesRemaining = maxRetries - retryCount;
 					LOGGER.info(String.format("Re-issuing request to peer %s (%d attempt%s remaining)", peer, triesRemaining, (triesRemaining != 1 ? "s" : "")));
 					continue;
 				}

src/main/java/org/qortal/controller/tradebot/LitecoinACCTv1TradeBot.java

@@ -211,6 +211,9 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 
 		TradeBot.updateTradeBotState(repository, tradeBotData, () -> String.format("Built AT %s. Waiting for deployment", atAddress));
 
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository);
+
 		// Return to user for signing and broadcast as we don't have their Qortal private key
 		try {
 			return DeployAtTransactionTransformer.toBytes(deployAtTransactionData);
@@ -283,6 +286,9 @@ public class LitecoinACCTv1TradeBot implements AcctTradeBot {
 				tradeForeignPublicKey, tradeForeignPublicKeyHash,
 				crossChainTradeData.expectedForeignAmount, xprv58, null, lockTimeA, receivingPublicKeyHash);
 
+		// Attempt to backup the trade bot data
+		TradeBot.backupTradeBotData(repository);
+
 		// Check we have enough funds via xprv58 to fund P2SH to cover expectedForeignAmount
 		long p2shFee;
 		try {

src/main/java/org/qortal/controller/tradebot/TradeBot.java

@@ -7,6 +7,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Random;
+import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -267,6 +268,16 @@ public class TradeBot implements Listener {
 		return secret;
 	}
 
+	/*package*/ static void backupTradeBotData(Repository repository) {
+		// Attempt to backup the trade bot data. This an optional step and doesn't impact trading, so don't throw an exception on failure
+		try {
+			LOGGER.info("About to backup trade bot data...");
+			repository.exportNodeLocalData();
+		} catch (DataException e) {
+			LOGGER.info(String.format("Repository issue when exporting trade bot data: %s", e.getMessage()));
+		}
+	}
+
 	/** Updates trade-bot entry to new state, with current timestamp, logs message and notifies state-change listeners. */
 	/*package*/ static void updateTradeBotState(Repository repository, TradeBotData tradeBotData,
 			String newState, int newStateValue, Supplier<String> logMessageSupplier) throws DataException {

src/main/java/org/qortal/crosschain/Bitcoin.java

@@ -42,35 +42,32 @@ public class Bitcoin extends Bitcoiny {
 			public Collection<ElectrumX.Server> getServers() {
 				return Arrays.asList(
 						// Servers chosen on NO BASIS WHATSOEVER from various sources!
-						new Server("enode.duckdns.org", Server.ConnectionType.SSL, 50002),
-						new Server("electrumx.ml", Server.ConnectionType.SSL, 50002),
-						new Server("electrum.bitkoins.nl", Server.ConnectionType.SSL, 50512),
-						new Server("btc.electroncash.dk", Server.ConnectionType.SSL, 60002),
-						new Server("electrumx.electricnewyear.net", Server.ConnectionType.SSL, 50002),
-						new Server("dxm.no-ip.biz", Server.ConnectionType.TCP, 50001),
-						new Server("kirsche.emzy.de", Server.ConnectionType.TCP, 50001),
-						new Server("2AZZARITA.hopto.org", Server.ConnectionType.TCP, 50001),
-						new Server("xtrum.com", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.srvmin.network", Server.ConnectionType.TCP, 50001),
-						new Server("electrumx.alexridevski.net", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.lukechilds.co", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.poiuty.com", Server.ConnectionType.TCP, 50001),
-						new Server("horsey.cryptocowboys.net", Server.ConnectionType.TCP, 50001),
+						new Server("128.0.190.26", Server.ConnectionType.SSL, 50002),
+						new Server("hodlers.beer", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.erbium.eu", Server.ConnectionType.TCP, 50001),
+						new Server("electrumx.erbium.eu", Server.ConnectionType.SSL, 50002),
+						new Server("btc.lastingcoin.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.bitaroo.net", Server.ConnectionType.SSL, 50002),
+						new Server("bitcoin.grey.pw", Server.ConnectionType.SSL, 50002),
+						new Server("2electrumx.hopto.me", Server.ConnectionType.SSL, 56022),
+						new Server("185.64.116.15", Server.ConnectionType.SSL, 50002),
+						new Server("kirsche.emzy.de", Server.ConnectionType.SSL, 50002),
+						new Server("alviss.coinjoined.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.emzy.de", Server.ConnectionType.SSL, 50002),
 						new Server("electrum.emzy.de", Server.ConnectionType.TCP, 50001),
-						new Server("electrum-server.ninja", Server.ConnectionType.TCP, 50081),
-						new Server("bitcoin.electrumx.multicoin.co", Server.ConnectionType.TCP, 50001),
-						new Server("esx.geekhosters.com", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.grey.pw", Server.ConnectionType.TCP, 50003),
-						new Server("exs.ignorelist.com", Server.ConnectionType.TCP, 50001),
-						new Server("electrum.coinext.com.br", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.aranguren.org", Server.ConnectionType.TCP, 50001),
-						new Server("skbxmit.coinjoined.com", Server.ConnectionType.TCP, 50001),
-						new Server("alviss.coinjoined.com", Server.ConnectionType.TCP, 50001),
-						new Server("electrum2.privateservers.network", Server.ConnectionType.TCP, 50001),
-						new Server("electrumx.schulzemic.net", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoins.sk", Server.ConnectionType.TCP, 56001),
-						new Server("node.mendonca.xyz", Server.ConnectionType.TCP, 50001),
-						new Server("bitcoin.aranguren.org", Server.ConnectionType.TCP, 50001));
+						new Server("vmd71287.contaboserver.net", Server.ConnectionType.SSL, 50002),
+						new Server("btc.litepay.ch", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.stippy.com", Server.ConnectionType.SSL, 50002),
+						new Server("xtrum.com", Server.ConnectionType.SSL, 50002),
+						new Server("electrum.acinq.co", Server.ConnectionType.SSL, 50002),
+						new Server("electrum2.taborsky.cz", Server.ConnectionType.SSL, 50002),
+						new Server("vmd63185.contaboserver.net", Server.ConnectionType.SSL, 50002),
+						new Server("electrum2.privateservers.network", Server.ConnectionType.SSL, 50002),
+						new Server("electrumx.alexridevski.net", Server.ConnectionType.SSL, 50002),
+						new Server("192.166.219.200", Server.ConnectionType.SSL, 50002),
+						new Server("2ex.digitaleveryware.com", Server.ConnectionType.SSL, 50002),
+						new Server("dxm.no-ip.biz", Server.ConnectionType.SSL, 50002),
+						new Server("caleb.vegas", Server.ConnectionType.SSL, 50002));
 			}
 
 			@Override
@@ -96,10 +93,8 @@ public class Bitcoin extends Bitcoiny {
 			@Override
 			public Collection<ElectrumX.Server> getServers() {
 				return Arrays.asList(
-						new Server("electrum.blockstream.info", Server.ConnectionType.TCP, 60001),
-						new Server("electrum.blockstream.info", Server.ConnectionType.SSL, 60002),
+						new Server("tn.not.fyi", Server.ConnectionType.SSL, 55002),
 						new Server("electrumx-test.1209k.com", Server.ConnectionType.SSL, 50002),
-						new Server("testnet.qtornado.com", Server.ConnectionType.TCP, 51001),
 						new Server("testnet.qtornado.com", Server.ConnectionType.SSL, 51002),
 						new Server("testnet.aranguren.org", Server.ConnectionType.TCP, 51001),
 						new Server("testnet.aranguren.org", Server.ConnectionType.SSL, 51002),

src/main/java/org/qortal/data/block/BlockSummaryData.java

@@ -2,6 +2,7 @@ package org.qortal.data.block;
 
 import javax.xml.bind.annotation.XmlAccessType;
 import javax.xml.bind.annotation.XmlAccessorType;
+import java.util.Arrays;
 
 @XmlAccessorType(XmlAccessType.FIELD)
 public class BlockSummaryData {
@@ -84,4 +85,21 @@ public class BlockSummaryData {
 		this.minterLevel = minterLevel;
 	}
 
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o)
+			return true;
+
+		if (o == null || getClass() != o.getClass())
+			return false;
+
+		BlockSummaryData otherBlockSummary = (BlockSummaryData) o;
+		if (this.getSignature() == null || otherBlockSummary.getSignature() == null)
+			return false;
+
+		// Treat two block summaries as equal if they have matching signatures
+		return Arrays.equals(this.getSignature(), otherBlockSummary.getSignature());
+	}
+
 }

src/main/java/org/qortal/data/block/CommonBlockData.java

@@ -0,0 +1,56 @@
+package org.qortal.data.block;
+
+import org.qortal.data.network.PeerChainTipData;
+
+import javax.xml.bind.annotation.XmlAccessType;
+import javax.xml.bind.annotation.XmlAccessorType;
+import java.math.BigInteger;
+import java.util.List;
+
+@XmlAccessorType(XmlAccessType.FIELD)
+public class CommonBlockData {
+
+	// Properties
+	private BlockSummaryData commonBlockSummary = null;
+	private List<BlockSummaryData> blockSummariesAfterCommonBlock = null;
+	private BigInteger chainWeight = null;
+	private PeerChainTipData chainTipData = null;
+
+	// Constructors
+
+	protected CommonBlockData() {
+	}
+
+	public CommonBlockData(BlockSummaryData commonBlockSummary, PeerChainTipData chainTipData) {
+		this.commonBlockSummary = commonBlockSummary;
+		this.chainTipData = chainTipData;
+	}
+
+
+	// Getters / setters
+
+	public BlockSummaryData getCommonBlockSummary() {
+		return this.commonBlockSummary;
+	}
+
+	public List<BlockSummaryData> getBlockSummariesAfterCommonBlock() {
+		return this.blockSummariesAfterCommonBlock;
+	}
+
+	public void setBlockSummariesAfterCommonBlock(List<BlockSummaryData> blockSummariesAfterCommonBlock) {
+		this.blockSummariesAfterCommonBlock = blockSummariesAfterCommonBlock;
+	}
+
+	public BigInteger getChainWeight() {
+		return this.chainWeight;
+	}
+
+	public void setChainWeight(BigInteger chainWeight) {
+		this.chainWeight = chainWeight;
+	}
+
+	public PeerChainTipData getChainTipData() {
+		return this.chainTipData;
+	}
+
+}

src/main/java/org/qortal/data/crosschain/TradeBotData.java

@@ -6,6 +6,9 @@ import javax.xml.bind.annotation.XmlTransient;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 import io.swagger.v3.oas.annotations.media.Schema;
+import org.json.JSONObject;
+
+import org.qortal.utils.Base58;
 
 // All properties to be converted to JSON via JAXB
 @XmlAccessorType(XmlAccessType.FIELD)
@@ -205,6 +208,58 @@ public class TradeBotData {
 		return this.receivingAccountInfo;
 	}
 
+	public JSONObject toJson() {
+		JSONObject jsonObject = new JSONObject();
+		jsonObject.put("tradePrivateKey", Base58.encode(this.getTradePrivateKey()));
+		jsonObject.put("acctName", this.getAcctName());
+		jsonObject.put("tradeState", this.getState());
+		jsonObject.put("tradeStateValue", this.getStateValue());
+		jsonObject.put("creatorAddress", this.getCreatorAddress());
+		jsonObject.put("atAddress", this.getAtAddress());
+		jsonObject.put("timestamp", this.getTimestamp());
+		jsonObject.put("qortAmount", this.getQortAmount());
+		if (this.getTradeNativePublicKey() != null) jsonObject.put("tradeNativePublicKey", Base58.encode(this.getTradeNativePublicKey()));
+		if (this.getTradeNativePublicKeyHash() != null) jsonObject.put("tradeNativePublicKeyHash", Base58.encode(this.getTradeNativePublicKeyHash()));
+		jsonObject.put("tradeNativeAddress", this.getTradeNativeAddress());
+		if (this.getSecret() != null) jsonObject.put("secret", Base58.encode(this.getSecret()));
+		if (this.getHashOfSecret() != null) jsonObject.put("hashOfSecret", Base58.encode(this.getHashOfSecret()));
+		jsonObject.put("foreignBlockchain", this.getForeignBlockchain());
+		if (this.getTradeForeignPublicKey() != null) jsonObject.put("tradeForeignPublicKey", Base58.encode(this.getTradeForeignPublicKey()));
+		if (this.getTradeForeignPublicKeyHash() != null) jsonObject.put("tradeForeignPublicKeyHash", Base58.encode(this.getTradeForeignPublicKeyHash()));
+		jsonObject.put("foreignKey", this.getForeignKey());
+        jsonObject.put("foreignAmount", this.getForeignAmount());
+		if (this.getLastTransactionSignature() != null) jsonObject.put("lastTransactionSignature", Base58.encode(this.getLastTransactionSignature()));
+        jsonObject.put("lockTimeA", this.getLockTimeA());
+		if (this.getReceivingAccountInfo() != null) jsonObject.put("receivingAccountInfo", Base58.encode(this.getReceivingAccountInfo()));
+		return jsonObject;
+	}
+
+	public static TradeBotData fromJson(JSONObject json) {
+		return new TradeBotData(
+				json.isNull("tradePrivateKey") ? null : Base58.decode(json.getString("tradePrivateKey")),
+				json.isNull("acctName") ? null : json.getString("acctName"),
+				json.isNull("tradeState") ? null : json.getString("tradeState"),
+				json.isNull("tradeStateValue") ? null : json.getInt("tradeStateValue"),
+				json.isNull("creatorAddress") ? null : json.getString("creatorAddress"),
+				json.isNull("atAddress") ? null : json.getString("atAddress"),
+				json.isNull("timestamp") ? null : json.getLong("timestamp"),
+				json.isNull("qortAmount") ? null : json.getLong("qortAmount"),
+				json.isNull("tradeNativePublicKey") ? null : Base58.decode(json.getString("tradeNativePublicKey")),
+				json.isNull("tradeNativePublicKeyHash") ? null : Base58.decode(json.getString("tradeNativePublicKeyHash")),
+				json.isNull("tradeNativeAddress") ? null : json.getString("tradeNativeAddress"),
+				json.isNull("secret") ? null : Base58.decode(json.getString("secret")),
+				json.isNull("hashOfSecret") ? null : Base58.decode(json.getString("hashOfSecret")),
+				json.isNull("foreignBlockchain") ? null : json.getString("foreignBlockchain"),
+				json.isNull("tradeForeignPublicKey") ? null : Base58.decode(json.getString("tradeForeignPublicKey")),
+				json.isNull("tradeForeignPublicKeyHash") ? null : Base58.decode(json.getString("tradeForeignPublicKeyHash")),
+				json.isNull("foreignAmount") ? null : json.getLong("foreignAmount"),
+				json.isNull("foreignKey") ? null : json.getString("foreignKey"),
+				json.isNull("lastTransactionSignature") ? null : Base58.decode(json.getString("lastTransactionSignature")),
+				json.isNull("lockTimeA") ? null : json.getInt("lockTimeA"),
+				json.isNull("receivingAccountInfo") ? null : Base58.decode(json.getString("receivingAccountInfo"))
+		);
+	}
+
 	// Mostly for debugging
 	public String toString() {
 		return String.format("%s: %s (%d)", this.atAddress, this.tradeState, this.tradeStateValue);

src/main/java/org/qortal/network/Handshake.java

@@ -4,7 +4,6 @@ import java.util.Arrays;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -51,7 +50,7 @@ public enum Handshake {
 
 			String versionString = helloMessage.getVersionString();
 
-			Matcher matcher = VERSION_PATTERN.matcher(versionString);
+			Matcher matcher = peer.VERSION_PATTERN.matcher(versionString);
 			if (!matcher.lookingAt()) {
 				LOGGER.debug(() -> String.format("Peer %s sent invalid HELLO version string '%s'", peer, versionString));
 				return null;
@@ -72,6 +71,15 @@ public enum Handshake {
 			peer.setPeersConnectionTimestamp(peersConnectionTimestamp);
 			peer.setPeersVersion(versionString, version);
 
+			if (Settings.getInstance().getAllowConnectionsWithOlderPeerVersions() == false) {
+				// Ensure the peer is running at least the minimum version allowed for connections
+				final String minPeerVersion = Settings.getInstance().getMinPeerVersion();
+				if (peer.isAtLeastVersion(minPeerVersion) == false) {
+					LOGGER.debug(String.format("Ignoring peer %s because it is on an old version (%s)", peer, versionString));
+					return null;
+				}
+			}
+
 			return CHALLENGE;
 		}
 
@@ -244,8 +252,6 @@ public enum Handshake {
 	/** Maximum allowed difference between peer's reported timestamp and when they connected, in milliseconds. */
 	private static final long MAX_TIMESTAMP_DELTA = 30 * 1000L; // ms
 
-	private static final Pattern VERSION_PATTERN = Pattern.compile(Controller.VERSION_PREFIX + "(\\d{1,3})\\.(\\d{1,5})\\.(\\d{1,5})");
-
 	private static final long PEER_VERSION_131 = 0x0100030001L;
 
 	private static final int POW_BUFFER_SIZE_PRE_131 = 8 * 1024 * 1024; // bytes

src/main/java/org/qortal/network/Peer.java

@@ -15,13 +15,18 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Random;
+import java.util.Arrays;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.qortal.controller.Controller;
+import org.qortal.data.block.CommonBlockData;
 import org.qortal.data.network.PeerChainTipData;
 import org.qortal.data.network.PeerData;
 import org.qortal.network.message.ChallengeMessage;
@@ -85,6 +90,9 @@ public class Peer {
 
 	byte[] ourChallenge;
 
+	// Versioning
+	public static final Pattern VERSION_PATTERN = Pattern.compile(Controller.VERSION_PREFIX + "(\\d{1,3})\\.(\\d{1,5})\\.(\\d{1,5})");
+
 	// Peer info
 
 	private final Object peerInfoLock = new Object();
@@ -106,6 +114,9 @@ public class Peer {
 	/** Latest block info as reported by peer. */
 	private PeerChainTipData peersChainTipData;
 
+	/** Our common block with this peer */
+	private CommonBlockData commonBlockData;
+
 	// Constructors
 
 	/** Construct unconnected, outbound Peer using socket address in peer data */
@@ -272,6 +283,18 @@ public class Peer {
 		}
 	}
 
+	public CommonBlockData getCommonBlockData() {
+		synchronized (this.peerInfoLock) {
+			return this.commonBlockData;
+		}
+	}
+
+	public void setCommonBlockData(CommonBlockData commonBlockData) {
+		synchronized (this.peerInfoLock) {
+			this.commonBlockData = commonBlockData;
+		}
+	}
+
 	/*package*/ void queueMessage(Message message) {
 		if (!this.pendingMessages.offer(message))
 			LOGGER.info(() -> String.format("No room to queue message from peer %s - discarding", this));
@@ -616,6 +639,54 @@ public class Peer {
 		}
 	}
 
+
+	// Minimum version
+
+	public boolean isAtLeastVersion(String minVersionString) {
+		if (minVersionString == null)
+			return false;
+
+		// Add the version prefix
+		minVersionString = Controller.VERSION_PREFIX + minVersionString;
+
+		Matcher matcher = VERSION_PATTERN.matcher(minVersionString);
+		if (!matcher.lookingAt())
+			return false;
+
+		// We're expecting 3 positive shorts, so we can convert 1.2.3 into 0x0100020003
+		long minVersion = 0;
+		for (int g = 1; g <= 3; ++g) {
+			long value = Long.parseLong(matcher.group(g));
+
+			if (value < 0 || value > Short.MAX_VALUE)
+				return false;
+
+			minVersion <<= 16;
+			minVersion |= value;
+		}
+
+		return this.getPeersVersion() >= minVersion;
+	}
+
+
+	// Common block data
+
+	public boolean canUseCachedCommonBlockData() {
+		PeerChainTipData peerChainTipData = this.getChainTipData();
+		CommonBlockData commonBlockData = this.getCommonBlockData();
+
+		if (peerChainTipData != null && commonBlockData != null) {
+			PeerChainTipData commonBlockChainTipData = commonBlockData.getChainTipData();
+			if (peerChainTipData.getLastBlockSignature() != null && commonBlockChainTipData != null && commonBlockChainTipData.getLastBlockSignature() != null) {
+				if (Arrays.equals(peerChainTipData.getLastBlockSignature(), commonBlockChainTipData.getLastBlockSignature())) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+
+
 	// Utility methods
 
 	/** Returns true if ports and addresses (or hostnames) match */

src/main/java/org/qortal/repository/ATRepository.java

@@ -98,7 +98,7 @@ public interface ATRepository {
 	 */
 	public List<ATStateData> getMatchingFinalATStatesQuorum(byte[] codeHash, Boolean isFinished,
 			Integer dataByteOffset, Long expectedValue,
-			int minimumCount, long minimumPeriod) throws DataException;
+			int minimumCount, int maximumCount, long minimumPeriod) throws DataException;
 
 	/**
 	 * Returns all ATStateData for a given block height.

src/main/java/org/qortal/repository/hsqldb/HSQLDBATRepository.java

@@ -454,7 +454,7 @@ public class HSQLDBATRepository implements ATRepository {
 	@Override
 	public List<ATStateData> getMatchingFinalATStatesQuorum(byte[] codeHash, Boolean isFinished,
 			Integer dataByteOffset, Long expectedValue,
-			int minimumCount, long minimumPeriod) throws DataException {
+			int minimumCount, int maximumCount, long minimumPeriod) throws DataException {
 		// We need most recent entry first so we can use its timestamp to slice further results
 		List<ATStateData> mostRecentStates = this.getMatchingFinalATStates(codeHash, isFinished,
 				dataByteOffset, expectedValue, null,
@@ -510,7 +510,8 @@ public class HSQLDBATRepository implements ATRepository {
 		bindParams.add(minimumHeight);
 		bindParams.add(minimumCount);
 
-		sql.append("ORDER BY FinalATStates.height DESC");
+		sql.append("ORDER BY FinalATStates.height DESC LIMIT ?");
+		bindParams.add(maximumCount);
 
 		List<ATStateData> atStates = new ArrayList<>();
 

src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java

@@ -2,6 +2,7 @@ package org.qortal.repository.hsqldb;
 
 import java.awt.TrayIcon.MessageType;
 import java.io.File;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.math.BigDecimal;
 import java.nio.file.Files;
@@ -15,23 +16,19 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Savepoint;
 import java.sql.Statement;
-import java.util.ArrayDeque;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.Deque;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
+import org.json.JSONArray;
+import org.json.JSONObject;
+
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.account.PrivateKeyAccount;
 import org.qortal.crypto.Crypto;
+import org.qortal.data.crosschain.TradeBotData;
 import org.qortal.globalization.Translator;
 import org.qortal.gui.SysTray;
 import org.qortal.repository.ATRepository;
@@ -52,6 +49,7 @@ import org.qortal.repository.TransactionRepository;
 import org.qortal.repository.VotingRepository;
 import org.qortal.repository.hsqldb.transaction.HSQLDBTransactionRepository;
 import org.qortal.settings.Settings;
+import org.qortal.utils.Base58;
 
 public class HSQLDBRepository implements Repository {
 
@@ -460,28 +458,68 @@ public class HSQLDBRepository implements Repository {
 
 	@Override
 	public void exportNodeLocalData() throws DataException {
-		try (Statement stmt = this.connection.createStatement()) {
-			stmt.execute("PERFORM EXPORT SCRIPT FOR TABLE MintingAccounts DATA TO 'MintingAccounts.script'");
-			stmt.execute("PERFORM EXPORT SCRIPT FOR TABLE TradeBotStates DATA TO 'TradeBotStates.script'");
-			LOGGER.info("Exported sensitive/node-local data: minting keys and trade bot states");
-		} catch (SQLException e) {
-			throw new DataException("Unable to export sensitive/node-local data from repository");
+		// Create the qortal-backup folder if it doesn't exist
+		Path backupPath = Paths.get("qortal-backup");
+		try {
+			Files.createDirectories(backupPath);
+		} catch (IOException e) {
+			LOGGER.info("Unable to create backup folder");
+			throw new DataException("Unable to create backup folder");
+		}
+
+		try {
+			// Load trade bot data
+			List<TradeBotData> allTradeBotData = this.getCrossChainRepository().getAllTradeBotData();
+			JSONArray allTradeBotDataJson = new JSONArray();
+			for (TradeBotData tradeBotData : allTradeBotData) {
+				JSONObject tradeBotDataJson = tradeBotData.toJson();
+				allTradeBotDataJson.put(tradeBotDataJson);
+			}
+
+			// We need to combine existing TradeBotStates data before overwriting
+			String fileName = "qortal-backup/TradeBotStates.json";
+			File tradeBotStatesBackupFile = new File(fileName);
+			if (tradeBotStatesBackupFile.exists()) {
+				String jsonString = new String(Files.readAllBytes(Paths.get(fileName)));
+				JSONArray allExistingTradeBotData = new JSONArray(jsonString);
+				Iterator<Object> iterator = allExistingTradeBotData.iterator();
+				while(iterator.hasNext()) {
+					JSONObject existingTradeBotData = (JSONObject)iterator.next();
+					String existingTradePrivateKey = (String) existingTradeBotData.get("tradePrivateKey");
+						// Check if we already have an entry for this trade
+						boolean found = allTradeBotData.stream().anyMatch(tradeBotData -> Base58.encode(tradeBotData.getTradePrivateKey()).equals(existingTradePrivateKey));
+						if (found == false)
+							// We need to add this to our list
+							allTradeBotDataJson.put(existingTradeBotData);
+				}
+			}
+
+			FileWriter writer = new FileWriter(fileName);
+			writer.write(allTradeBotDataJson.toString());
+			writer.close();
+			LOGGER.info("Exported sensitive/node-local data: trade bot states");
+
+		} catch (DataException | IOException e) {
+			throw new DataException("Unable to export trade bot states from repository");
 		}
 	}
 
 	@Override
 	public void importDataFromFile(String filename) throws DataException {
-		try (Statement stmt = this.connection.createStatement()) {
-			LOGGER.info(() -> String.format("Importing data into repository from %s", filename));
-
-			String escapedFilename = stmt.enquoteLiteral(filename);
-			stmt.execute("PERFORM IMPORT SCRIPT DATA FROM " + escapedFilename + " STOP ON ERROR");
-
-			LOGGER.info(() -> String.format("Imported data into repository from %s", filename));
-		} catch (SQLException e) {
-			LOGGER.info(() -> String.format("Failed to import data into repository from %s: %s", filename, e.getMessage()));
-			throw new DataException("Unable to export sensitive/node-local data from repository: " + e.getMessage());
+		LOGGER.info(() -> String.format("Importing data into repository from %s", filename));
+		try {
+			String jsonString = new String(Files.readAllBytes(Paths.get(filename)));
+			JSONArray tradeBotDataToImport = new JSONArray(jsonString);
+			Iterator<Object> iterator = tradeBotDataToImport.iterator();
+			while(iterator.hasNext()) {
+				JSONObject tradeBotDataJson = (JSONObject)iterator.next();
+				TradeBotData tradeBotData = TradeBotData.fromJson(tradeBotDataJson);
+				this.getCrossChainRepository().save(tradeBotData);
+			}
+		} catch (IOException e) {
+			throw new DataException("Unable to import sensitive/node-local trade bot states to repository: " + e.getMessage());
 		}
+		LOGGER.info(() -> String.format("Imported trade bot states into repository from %s", filename));
 	}
 
 	@Override
@@ -681,7 +719,7 @@ public class HSQLDBRepository implements Repository {
 	/**
 	 * Execute PreparedStatement and return changed row count.
 	 * 
-	 * @param preparedStatement
+	 * @param sql
 	 * @param objects
 	 * @return number of changed rows
 	 * @throws SQLException
@@ -693,8 +731,8 @@ public class HSQLDBRepository implements Repository {
 	/**
 	 * Execute batched PreparedStatement
 	 * 
-	 * @param preparedStatement
-	 * @param objects
+	 * @param sql
+	 * @param batchedObjects
 	 * @return number of changed rows
 	 * @throws SQLException
 	 */
@@ -818,7 +856,7 @@ public class HSQLDBRepository implements Repository {
 	 * 
 	 * @param tableName
 	 * @param whereClause
-	 * @param objects
+	 * @param batchedObjects
 	 * @throws SQLException
 	 */
 	public int deleteBatch(String tableName, String whereClause, List<Object[]> batchedObjects) throws SQLException {

src/main/java/org/qortal/settings/Settings.java

@@ -52,7 +52,7 @@ public class Settings {
 	// UI servers
 	private int uiPort = 12388;
 	private String[] uiLocalServers = new String[] {
-		"localhost", "127.0.0.1", "172.24.1.1", "qor.tal"
+		"localhost", "127.0.0.1"
 	};
 	private String[] uiRemoteServers = new String[] {
 		"node1.qortal.org", "node2.qortal.org", "node3.qortal.org", "node4.qortal.org", "node5.qortal.org",
@@ -122,6 +122,15 @@ public class Settings {
 	private int maxNetworkThreadPoolSize = 20;
 	/** Maximum number of threads for network proof-of-work compute, used during handshaking. */
 	private int networkPoWComputePoolSize = 2;
+	/** Maximum number of retry attempts if a peer fails to respond with the requested data */
+	private int maxRetries = 2;
+
+	/** Minimum peer version number required in order to sync with them */
+	private String minPeerVersion = "1.5.0";
+	/** Whether to allow connections with peers below minPeerVersion
+	 * If true, we won't sync with them but they can still sync with us, and will show in the peers list
+	 * If false, sync will be blocked both ways, and they will not appear in the peers list */
+	private boolean allowConnectionsWithOlderPeerVersions = true;
 
 	// Which blockchains this node is running
 	private String blockchainConfig = null; // use default from resources
@@ -408,6 +417,12 @@ public class Settings {
 		return this.networkPoWComputePoolSize;
 	}
 
+	public int getMaxRetries() { return this.maxRetries; }
+
+	public String getMinPeerVersion() { return this.minPeerVersion; }
+
+	public boolean getAllowConnectionsWithOlderPeerVersions() { return this.allowConnectionsWithOlderPeerVersions; }
+
 	public String getBlockchainConfig() {
 		return this.blockchainConfig;
 	}

src/main/resources/blockchain.json

@@ -49,7 +49,9 @@
 	},
 	"featureTriggers": {
 		"atFindNextTransactionFix": 275000,
-		"newBlockSigHeight": 320000
+		"newBlockSigHeight": 320000,
+		"shareBinFix": 399000,
+		"calcChainWeightTimestamp": 1620579600000
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/java/org/qortal/test/ChainWeightTests.java

@@ -3,12 +3,15 @@ package org.qortal.test;
 import static org.junit.Assert.*;
 
 import java.math.BigInteger;
+import java.text.DecimalFormat;
+import java.text.NumberFormat;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 
 import org.qortal.account.Account;
 import org.qortal.block.Block;
+import org.qortal.block.BlockChain;
 import org.qortal.data.block.BlockSummaryData;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
@@ -17,12 +20,21 @@ import org.qortal.test.common.Common;
 import org.qortal.test.common.TestAccount;
 import org.qortal.transform.Transformer;
 import org.qortal.transform.block.BlockTransformer;
+import org.qortal.utils.NTP;
 import org.junit.Before;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 public class ChainWeightTests extends Common {
 
 	private static final Random RANDOM = new Random();
+	private static final NumberFormat FORMATTER = new DecimalFormat("0.###E0");
+
+	@BeforeClass
+	public static void beforeClass() {
+		// We need this so that NTP.getTime() in Block.calcChainWeight() doesn't return null, causing NPE
+		NTP.setFixedOffset(0L);
+	}
 
 	@Before
 	public void beforeTest() throws DataException {
@@ -89,7 +101,97 @@ public class ChainWeightTests extends Common {
 		}
 	}
 
-	// Check that a longer chain beats a shorter chain
+	// Demonstrates that typical key distance ranges from roughly 1E75 to 1E77
+	@Test
+	public void testKeyDistances() {
+		byte[] parentMinterKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+		byte[] testKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+
+		for (int i = 0; i < 50; ++i) {
+			int parentHeight = RANDOM.nextInt(50000);
+			RANDOM.nextBytes(parentMinterKey);
+			RANDOM.nextBytes(testKey);
+			int minterLevel = RANDOM.nextInt(10) + 1;
+
+			BigInteger keyDistance = Block.calcKeyDistance(parentHeight, parentMinterKey, testKey, minterLevel);
+
+			System.out.println(String.format("Parent height: %d, minter level: %d, distance: %s",
+					parentHeight,
+					minterLevel,
+					FORMATTER.format(keyDistance)));
+		}
+	}
+
+	// If typical key distance ranges from 1E75 to 1E77
+	// then we want lots of online accounts to push a 1E75 distance
+	// towards 1E77 so that it competes with a 1E77 key that has hardly any online accounts
+	// 1E75 is approx. 2**249 so maybe that's a good value for Block.ACCOUNTS_COUNT_SHIFT
+	@Test
+	public void testMoreAccountsVersusKeyDistance() throws DataException {
+		BigInteger minimumBetterKeyDistance = BigInteger.TEN.pow(77);
+		BigInteger maximumWorseKeyDistance = BigInteger.TEN.pow(75);
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			final byte[] parentMinterKey = new byte[Transformer.PUBLIC_KEY_LENGTH];
+
+			TestAccount betterAccount = Common.getTestAccount(repository, "bob-reward-share");
+			byte[] betterKey = betterAccount.getPublicKey();
+			int betterMinterLevel = Account.getRewardShareEffectiveMintingLevel(repository, betterKey);
+
+			TestAccount worseAccount = Common.getTestAccount(repository, "dilbert-reward-share");
+			byte[] worseKey = worseAccount.getPublicKey();
+			int worseMinterLevel = Account.getRewardShareEffectiveMintingLevel(repository, worseKey);
+
+			// This is to check that the hard-coded keys ARE actually better/worse as expected, before moving on testing more online accounts
+			BigInteger betterKeyDistance;
+			BigInteger worseKeyDistance;
+
+			int parentHeight = 0;
+			do {
+				++parentHeight;
+				betterKeyDistance = Block.calcKeyDistance(parentHeight, parentMinterKey, betterKey, betterMinterLevel);
+				worseKeyDistance = Block.calcKeyDistance(parentHeight, parentMinterKey, worseKey, worseMinterLevel);
+			} while (betterKeyDistance.compareTo(minimumBetterKeyDistance) < 0 || worseKeyDistance.compareTo(maximumWorseKeyDistance) > 0);
+
+			System.out.println(String.format("Parent height: %d, better key distance: %s, worse key distance: %s",
+					parentHeight,
+					FORMATTER.format(betterKeyDistance),
+					FORMATTER.format(worseKeyDistance)));
+
+			for (int accountsCountShift = 244; accountsCountShift <= 256; accountsCountShift += 2) {
+				for (int worseAccountsCount = 1; worseAccountsCount <= 101; worseAccountsCount += 25) {
+					for (int betterAccountsCount = 1; betterAccountsCount <= 1001; betterAccountsCount += 250) {
+						BlockSummaryData worseKeyBlockSummary = new BlockSummaryData(parentHeight + 1, null, worseKey, betterAccountsCount);
+						BlockSummaryData betterKeyBlockSummary = new BlockSummaryData(parentHeight + 1, null, betterKey, worseAccountsCount);
+
+						populateBlockSummaryMinterLevel(repository, worseKeyBlockSummary);
+						populateBlockSummaryMinterLevel(repository, betterKeyBlockSummary);
+
+						BigInteger worseKeyBlockWeight = calcBlockWeight(parentHeight, parentMinterKey, worseKeyBlockSummary, accountsCountShift);
+						BigInteger betterKeyBlockWeight = calcBlockWeight(parentHeight, parentMinterKey, betterKeyBlockSummary, accountsCountShift);
+
+						System.out.println(String.format("Shift: %d, worse key: %d accounts, %s diff; better key: %d accounts: %s diff; winner: %s",
+								accountsCountShift,
+								betterAccountsCount, // used with worseKey
+								FORMATTER.format(worseKeyBlockWeight),
+								worseAccountsCount, // used with betterKey
+								FORMATTER.format(betterKeyBlockWeight),
+								worseKeyBlockWeight.compareTo(betterKeyBlockWeight) > 0 ? "worse key/better accounts" : "better key/worse accounts"
+								));
+					}
+				}
+
+				System.out.println();
+			}
+		}
+	}
+
+	private static BigInteger calcBlockWeight(int parentHeight, byte[] parentBlockSignature, BlockSummaryData blockSummaryData, int accountsCountShift) {
+		BigInteger keyDistance = Block.calcKeyDistance(parentHeight, parentBlockSignature, blockSummaryData.getMinterPublicKey(), blockSummaryData.getMinterLevel());
+		return BigInteger.valueOf(blockSummaryData.getOnlineAccountsCount()).shiftLeft(accountsCountShift).add(keyDistance);
+	}
+
+	// Check that a longer chain has same weight as shorter/truncated chain
 	@Test
 	public void testLongerChain() throws DataException {
 		try (final Repository repository = RepositoryManager.getRepository()) {
@@ -97,18 +199,20 @@ public class ChainWeightTests extends Common {
 			BlockSummaryData commonBlockSummary = genBlockSummary(repository, commonBlockHeight);
 			byte[] commonBlockGeneratorKey = commonBlockSummary.getMinterPublicKey();
 
-			List<BlockSummaryData> shorterChain = genBlockSummaries(repository, 3, commonBlockSummary);
-			List<BlockSummaryData> longerChain = genBlockSummaries(repository, shorterChain.size() + 1, commonBlockSummary);
-
-			populateBlockSummariesMinterLevels(repository, shorterChain);
+			List<BlockSummaryData> longerChain = genBlockSummaries(repository, 6, commonBlockSummary);
 			populateBlockSummariesMinterLevels(repository, longerChain);
 
+			List<BlockSummaryData> shorterChain = longerChain.subList(0, longerChain.size() / 2);
+
 			final int mutualHeight = commonBlockHeight - 1 + Math.min(shorterChain.size(), longerChain.size());
 
 			BigInteger shorterChainWeight = Block.calcChainWeight(commonBlockHeight, commonBlockGeneratorKey, shorterChain, mutualHeight);
 			BigInteger longerChainWeight = Block.calcChainWeight(commonBlockHeight, commonBlockGeneratorKey, longerChain, mutualHeight);
 
-			assertEquals("longer chain should have greater weight", 1, longerChainWeight.compareTo(shorterChainWeight));
+			if (NTP.getTime() >= BlockChain.getInstance().getCalcChainWeightTimestamp())
+				assertEquals("longer chain should have same weight", 0, longerChainWeight.compareTo(shorterChainWeight));
+			else
+				assertEquals("longer chain should have greater weight", 1, longerChainWeight.compareTo(shorterChainWeight));
 		}
 	}
 

src/test/java/org/qortal/test/minting/RewardTests.java

@@ -336,4 +336,457 @@ public class RewardTests extends Common {
 		}
 	}
 
+	/** Test rewards for level 1 and 2 accounts both pre and post the shareBinFix, including orphaning back through the feature trigger block */
+	@Test
+	public void testLevel1And2Rewards() throws DataException {
+		Common.useSettings("test-settings-v2-reward-levels.json");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			List<PrivateKeyAccount> mintingAndOnlineAccounts = new ArrayList<>();
+
+			// Alice self share online
+			PrivateKeyAccount aliceSelfShare = Common.getTestAccount(repository, "alice-reward-share");
+			mintingAndOnlineAccounts.add(aliceSelfShare);
+
+			// Bob self-share NOT online
+
+			// Chloe self share online
+			byte[] chloeRewardSharePrivateKey = AccountUtils.rewardShare(repository, "chloe", "chloe", 0);
+			PrivateKeyAccount chloeRewardShareAccount = new PrivateKeyAccount(repository, chloeRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(chloeRewardShareAccount);
+
+			// Dilbert self share online
+			byte[] dilbertRewardSharePrivateKey = AccountUtils.rewardShare(repository, "dilbert", "dilbert", 0);
+			PrivateKeyAccount dilbertRewardShareAccount = new PrivateKeyAccount(repository, dilbertRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(dilbertRewardShareAccount);
+
+			// Mint a couple of blocks so that we are able to orphan them later
+			for (int i=0; i<2; i++)
+				BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure that the levels are as we expect
+			assertEquals(1, (int) Common.getTestAccount(repository, "alice").getLevel());
+			assertEquals(1, (int) Common.getTestAccount(repository, "bob").getLevel());
+			assertEquals(1, (int) Common.getTestAccount(repository, "chloe").getLevel());
+			assertEquals(2, (int) Common.getTestAccount(repository, "dilbert").getLevel());
+
+			// Ensure that only Alice is a founder
+			assertEquals(1, getFlags(repository, "alice"));
+			assertEquals(0, getFlags(repository, "bob"));
+			assertEquals(0, getFlags(repository, "chloe"));
+			assertEquals(0, getFlags(repository, "dilbert"));
+
+			// Now that everyone is at level 1 or 2, we can capture initial balances
+			Map<String, Map<Long, Long>> initialBalances = AccountUtils.getBalances(repository, Asset.QORT, Asset.LEGACY_QORA, Asset.QORT_FROM_QORA);
+			final long aliceInitialBalance = initialBalances.get("alice").get(Asset.QORT);
+			final long bobInitialBalance = initialBalances.get("bob").get(Asset.QORT);
+			final long chloeInitialBalance = initialBalances.get("chloe").get(Asset.QORT);
+			final long dilbertInitialBalance = initialBalances.get("dilbert").get(Asset.QORT);
+
+			// Mint a block
+			final long blockReward = BlockUtils.getNextBlockReward(repository);
+			BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure we are at the correct height and block reward value
+			assertEquals(6, (int) repository.getBlockRepository().getLastBlock().getHeight());
+			assertEquals(10000000000L, blockReward);
+
+			/*
+			 * Alice, Chloe, and Dilbert are 'online'. Bob is offline.
+			 * Chloe is level 1, Dilbert is level 2.
+			 * One founder online (Alice, who is also level 1).
+			 * No legacy QORA holders.
+			 *
+			 * Chloe and Dilbert should receive equal shares of the 5% block reward for Level 1 and 2
+			 * Alice should receive the remainder (95%)
+			 */
+
+			// We are after the shareBinFix feature trigger, so we expect level 1 and 2 to share the same reward (5%)
+			final int level1And2SharePercent = 5_00; // 5%
+			final long level1And2ShareAmount = (blockReward * level1And2SharePercent) / 100L / 100L;
+			final long expectedReward = level1And2ShareAmount / 2; // The reward is split between Chloe and Dilbert
+			final long expectedFounderReward = blockReward - level1And2ShareAmount; // Alice should receive the remainder
+
+			// Validate the balances to ensure that the correct post-shareBinFix distribution is being applied
+			assertEquals(500000000, level1And2ShareAmount);
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance+expectedFounderReward);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance); // Bob not online so his balance remains the same
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance+expectedReward);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance+expectedReward);
+
+			// Now orphan the latest block. This brings us to the threshold of the shareBinFix feature trigger.
+			BlockUtils.orphanBlocks(repository, 1);
+			assertEquals(5, (int) repository.getBlockRepository().getLastBlock().getHeight());
+
+			// Ensure the latest post-fix block rewards have been subtracted and they have returned to their initial values
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance); // Bob not online so his balance remains the same
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance);
+
+			// Orphan another block. This time, the block that was orphaned was prior to the shareBinFix feature trigger.
+			BlockUtils.orphanBlocks(repository, 1);
+			assertEquals(4, (int) repository.getBlockRepository().getLastBlock().getHeight());
+
+			// Prior to the fix, the levels were incorrectly grouped
+			// Chloe should receive 100% of the level 1 reward, and Dilbert should receive 100% of the level 2+3 reward
+			final int level1SharePercent = 5_00; // 5%
+			final int level2And3SharePercent = 10_00; // 10%
+			final long level1ShareAmountBeforeFix = (blockReward * level1SharePercent) / 100L / 100L;
+			final long level2And3ShareAmountBeforeFix = (blockReward * level2And3SharePercent) / 100L / 100L;
+			final long expectedFounderRewardBeforeFix = blockReward - level1ShareAmountBeforeFix - level2And3ShareAmountBeforeFix; // Alice should receive the remainder
+
+			// Validate the share amounts and balances
+			assertEquals(500000000, level1ShareAmountBeforeFix);
+			assertEquals(1000000000, level2And3ShareAmountBeforeFix);
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance-expectedFounderRewardBeforeFix);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance); // Bob not online so his balance remains the same
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance-level1ShareAmountBeforeFix);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance-level2And3ShareAmountBeforeFix);
+
+			// Orphan the latest block one last time
+			BlockUtils.orphanBlocks(repository, 1);
+			assertEquals(3, (int) repository.getBlockRepository().getLastBlock().getHeight());
+
+			// Validate balances
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance-(expectedFounderRewardBeforeFix*2));
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance); // Bob not online so his balance remains the same
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance-(level1ShareAmountBeforeFix*2));
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance-(level2And3ShareAmountBeforeFix*2));
+
+		}
+	}
+
+	/** Test rewards for level 3 and 4 accounts */
+	@Test
+	public void testLevel3And4Rewards() throws DataException {
+		Common.useSettings("test-settings-v2-reward-levels.json");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			List<Integer> cumulativeBlocksByLevel = BlockChain.getInstance().getCumulativeBlocksByLevel();
+			List<PrivateKeyAccount> mintingAndOnlineAccounts = new ArrayList<>();
+
+			// Alice self share online
+			PrivateKeyAccount aliceSelfShare = Common.getTestAccount(repository, "alice-reward-share");
+			mintingAndOnlineAccounts.add(aliceSelfShare);
+
+			// Bob self-share online
+			byte[] bobRewardSharePrivateKey = AccountUtils.rewardShare(repository, "bob", "bob", 0);
+			PrivateKeyAccount bobRewardShareAccount = new PrivateKeyAccount(repository, bobRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(bobRewardShareAccount);
+
+			// Chloe self share online
+			byte[] chloeRewardSharePrivateKey = AccountUtils.rewardShare(repository, "chloe", "chloe", 0);
+			PrivateKeyAccount chloeRewardShareAccount = new PrivateKeyAccount(repository, chloeRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(chloeRewardShareAccount);
+
+			// Dilbert self share online
+			byte[] dilbertRewardSharePrivateKey = AccountUtils.rewardShare(repository, "dilbert", "dilbert", 0);
+			PrivateKeyAccount dilbertRewardShareAccount = new PrivateKeyAccount(repository, dilbertRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(dilbertRewardShareAccount);
+			
+			// Mint enough blocks to bump testAccount levels to 3 and 4
+			final int minterBlocksNeeded = cumulativeBlocksByLevel.get(4) - 20; // 20 blocks before level 4, so that the test accounts reach the correct levels
+			for (int bc = 0; bc < minterBlocksNeeded; ++bc)
+				BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure that the levels are as we expect
+			assertEquals(3, (int) Common.getTestAccount(repository, "alice").getLevel());
+			assertEquals(3, (int) Common.getTestAccount(repository, "bob").getLevel());
+			assertEquals(3, (int) Common.getTestAccount(repository, "chloe").getLevel());
+			assertEquals(4, (int) Common.getTestAccount(repository, "dilbert").getLevel());
+
+			// Now that everyone is at level 3 or 4, we can capture initial balances
+			Map<String, Map<Long, Long>> initialBalances = AccountUtils.getBalances(repository, Asset.QORT, Asset.LEGACY_QORA, Asset.QORT_FROM_QORA);
+			final long aliceInitialBalance = initialBalances.get("alice").get(Asset.QORT);
+			final long bobInitialBalance = initialBalances.get("bob").get(Asset.QORT);
+			final long chloeInitialBalance = initialBalances.get("chloe").get(Asset.QORT);
+			final long dilbertInitialBalance = initialBalances.get("dilbert").get(Asset.QORT);
+
+			// Mint a block
+			final long blockReward = BlockUtils.getNextBlockReward(repository);
+			BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure we are using the correct block reward value
+			assertEquals(100000000L, blockReward);
+
+			/*
+			 * Alice, Bob, Chloe, and Dilbert are 'online'.
+			 * Bob and Chloe are level 3; Dilbert is level 4.
+			 * One founder online (Alice, who is also level 3).
+			 * No legacy QORA holders.
+			 *
+			 * Chloe, Bob and Dilbert should receive equal shares of the 10% block reward for level 3 and 4
+			 * Alice should receive the remainder (90%)
+			 */
+
+			// We are after the shareBinFix feature trigger, so we expect level 3 and 4 to share the same reward (10%)
+			final int level3And4SharePercent = 10_00; // 10%
+			final long level3And4ShareAmount = (blockReward * level3And4SharePercent) / 100L / 100L;
+			final long expectedReward = level3And4ShareAmount / 3; // The reward is split between Bob, Chloe, and Dilbert
+			final long expectedFounderReward = blockReward - level3And4ShareAmount; // Alice should receive the remainder
+
+			// Validate the balances to ensure that the correct post-shareBinFix distribution is being applied
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance+expectedFounderReward);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance+expectedReward);
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance+expectedReward);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance+expectedReward);
+
+		}
+	}
+
+	/** Test rewards for level 5 and 6 accounts */
+	@Test
+	public void testLevel5And6Rewards() throws DataException {
+		Common.useSettings("test-settings-v2-reward-levels.json");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			List<Integer> cumulativeBlocksByLevel = BlockChain.getInstance().getCumulativeBlocksByLevel();
+			List<PrivateKeyAccount> mintingAndOnlineAccounts = new ArrayList<>();
+
+			// Alice self share online
+			PrivateKeyAccount aliceSelfShare = Common.getTestAccount(repository, "alice-reward-share");
+			mintingAndOnlineAccounts.add(aliceSelfShare);
+
+			// Bob self-share not initially online
+
+			// Chloe self share online
+			byte[] chloeRewardSharePrivateKey = AccountUtils.rewardShare(repository, "chloe", "chloe", 0);
+			PrivateKeyAccount chloeRewardShareAccount = new PrivateKeyAccount(repository, chloeRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(chloeRewardShareAccount);
+
+			// Dilbert self share online
+			byte[] dilbertRewardSharePrivateKey = AccountUtils.rewardShare(repository, "dilbert", "dilbert", 0);
+			PrivateKeyAccount dilbertRewardShareAccount = new PrivateKeyAccount(repository, dilbertRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(dilbertRewardShareAccount);
+
+			// Mint enough blocks to bump testAccount levels to 5 and 6
+			final int minterBlocksNeeded = cumulativeBlocksByLevel.get(6) - 20; // 20 blocks before level 6, so that the test accounts reach the correct levels
+			for (int bc = 0; bc < minterBlocksNeeded; ++bc)
+				BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Bob self-share now comes online
+			byte[] bobRewardSharePrivateKey = AccountUtils.rewardShare(repository, "bob", "bob", 0);
+			PrivateKeyAccount bobRewardShareAccount = new PrivateKeyAccount(repository, bobRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(bobRewardShareAccount);
+
+			// Ensure that the levels are as we expect
+			assertEquals(5, (int) Common.getTestAccount(repository, "alice").getLevel());
+			assertEquals(1, (int) Common.getTestAccount(repository, "bob").getLevel());
+			assertEquals(5, (int) Common.getTestAccount(repository, "chloe").getLevel());
+			assertEquals(6, (int) Common.getTestAccount(repository, "dilbert").getLevel());
+
+			// Now that everyone is at level 5 or 6 (except Bob who has only just started minting, so is at level 1), we can capture initial balances
+			Map<String, Map<Long, Long>> initialBalances = AccountUtils.getBalances(repository, Asset.QORT, Asset.LEGACY_QORA, Asset.QORT_FROM_QORA);
+			final long aliceInitialBalance = initialBalances.get("alice").get(Asset.QORT);
+			final long bobInitialBalance = initialBalances.get("bob").get(Asset.QORT);
+			final long chloeInitialBalance = initialBalances.get("chloe").get(Asset.QORT);
+			final long dilbertInitialBalance = initialBalances.get("dilbert").get(Asset.QORT);
+
+			// Mint a block
+			final long blockReward = BlockUtils.getNextBlockReward(repository);
+			BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure we are using the correct block reward value
+			assertEquals(100000000L, blockReward);
+
+			/*
+			 * Alice, Bob, Chloe, and Dilbert are 'online'.
+			 * Bob is level 1; Chloe is level 5; Dilbert is level 6.
+			 * One founder online (Alice, who is also level 5).
+			 * No legacy QORA holders.
+			 *
+			 * Chloe and Dilbert should receive equal shares of the 15% block reward for level 5 and 6
+			 * Bob should receive all of the level 1 and 2 reward (5%)
+			 * Alice should receive the remainder (80%)
+			 */
+
+			// We are after the shareBinFix feature trigger, so we expect level 5 and 6 to share the same reward (15%)
+			final int level1And2SharePercent = 5_00; // 5%
+			final int level5And6SharePercent = 15_00; // 10%
+			final long level1And2ShareAmount = (blockReward * level1And2SharePercent) / 100L / 100L;
+			final long level5And6ShareAmount = (blockReward * level5And6SharePercent) / 100L / 100L;
+			final long expectedLevel1And2Reward = level1And2ShareAmount; // The reward is given entirely to Bob
+			final long expectedLevel5And6Reward = level5And6ShareAmount / 2; // The reward is split between Chloe and Dilbert
+			final long expectedFounderReward = blockReward - level1And2ShareAmount - level5And6ShareAmount; // Alice should receive the remainder
+
+			// Validate the balances to ensure that the correct post-shareBinFix distribution is being applied
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance+expectedFounderReward);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance+expectedLevel1And2Reward);
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance+expectedLevel5And6Reward);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance+expectedLevel5And6Reward);
+
+		}
+	}
+
+	/** Test rewards for level 7 and 8 accounts */
+	@Test
+	public void testLevel7And8Rewards() throws DataException {
+		Common.useSettings("test-settings-v2-reward-levels.json");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			List<Integer> cumulativeBlocksByLevel = BlockChain.getInstance().getCumulativeBlocksByLevel();
+			List<PrivateKeyAccount> mintingAndOnlineAccounts = new ArrayList<>();
+
+			// Alice self share online
+			PrivateKeyAccount aliceSelfShare = Common.getTestAccount(repository, "alice-reward-share");
+			mintingAndOnlineAccounts.add(aliceSelfShare);
+
+			// Bob self-share NOT online
+
+			// Chloe self share online
+			byte[] chloeRewardSharePrivateKey = AccountUtils.rewardShare(repository, "chloe", "chloe", 0);
+			PrivateKeyAccount chloeRewardShareAccount = new PrivateKeyAccount(repository, chloeRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(chloeRewardShareAccount);
+
+			// Dilbert self share online
+			byte[] dilbertRewardSharePrivateKey = AccountUtils.rewardShare(repository, "dilbert", "dilbert", 0);
+			PrivateKeyAccount dilbertRewardShareAccount = new PrivateKeyAccount(repository, dilbertRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(dilbertRewardShareAccount);
+
+			// Mint enough blocks to bump testAccount levels to 7 and 8
+			final int minterBlocksNeeded = cumulativeBlocksByLevel.get(8) - 20; // 20 blocks before level 8, so that the test accounts reach the correct levels
+			for (int bc = 0; bc < minterBlocksNeeded; ++bc)
+				BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure that the levels are as we expect
+			assertEquals(7, (int) Common.getTestAccount(repository, "alice").getLevel());
+			assertEquals(1, (int) Common.getTestAccount(repository, "bob").getLevel());
+			assertEquals(7, (int) Common.getTestAccount(repository, "chloe").getLevel());
+			assertEquals(8, (int) Common.getTestAccount(repository, "dilbert").getLevel());
+
+			// Now that everyone is at level 7 or 8 (except Bob who has only just started minting, so is at level 1), we can capture initial balances
+			Map<String, Map<Long, Long>> initialBalances = AccountUtils.getBalances(repository, Asset.QORT, Asset.LEGACY_QORA, Asset.QORT_FROM_QORA);
+			final long aliceInitialBalance = initialBalances.get("alice").get(Asset.QORT);
+			final long bobInitialBalance = initialBalances.get("bob").get(Asset.QORT);
+			final long chloeInitialBalance = initialBalances.get("chloe").get(Asset.QORT);
+			final long dilbertInitialBalance = initialBalances.get("dilbert").get(Asset.QORT);
+
+			// Mint a block
+			final long blockReward = BlockUtils.getNextBlockReward(repository);
+			BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure we are using the correct block reward value
+			assertEquals(100000000L, blockReward);
+
+			/*
+			 * Alice, Chloe, and Dilbert are 'online'.
+			 * Chloe is level 7; Dilbert is level 8.
+			 * One founder online (Alice, who is also level 7).
+			 * No legacy QORA holders.
+			 *
+			 * Chloe and Dilbert should receive equal shares of the 20% block reward for level 7 and 8
+			 * Alice should receive the remainder (80%)
+			 */
+
+			// We are after the shareBinFix feature trigger, so we expect level 7 and 8 to share the same reward (20%)
+			final int level7And8SharePercent = 20_00; // 20%
+			final long level7And8ShareAmount = (blockReward * level7And8SharePercent) / 100L / 100L;
+			final long expectedLevel7And8Reward = level7And8ShareAmount / 2; // The reward is split between Chloe and Dilbert
+			final long expectedFounderReward = blockReward - level7And8ShareAmount; // Alice should receive the remainder
+
+			// Validate the balances to ensure that the correct post-shareBinFix distribution is being applied
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance+expectedFounderReward);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance); // Bob not online so his balance remains the same
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance+expectedLevel7And8Reward);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance+expectedLevel7And8Reward);
+
+		}
+	}
+
+	/** Test rewards for level 9 and 10 accounts */
+	@Test
+	public void testLevel9And10Rewards() throws DataException {
+		Common.useSettings("test-settings-v2-reward-levels.json");
+
+		try (final Repository repository = RepositoryManager.getRepository()) {
+
+			List<Integer> cumulativeBlocksByLevel = BlockChain.getInstance().getCumulativeBlocksByLevel();
+			List<PrivateKeyAccount> mintingAndOnlineAccounts = new ArrayList<>();
+
+			// Alice self share online
+			PrivateKeyAccount aliceSelfShare = Common.getTestAccount(repository, "alice-reward-share");
+			mintingAndOnlineAccounts.add(aliceSelfShare);
+
+			// Bob self-share not initially online
+
+			// Chloe self share online
+			byte[] chloeRewardSharePrivateKey = AccountUtils.rewardShare(repository, "chloe", "chloe", 0);
+			PrivateKeyAccount chloeRewardShareAccount = new PrivateKeyAccount(repository, chloeRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(chloeRewardShareAccount);
+
+			// Dilbert self share online
+			byte[] dilbertRewardSharePrivateKey = AccountUtils.rewardShare(repository, "dilbert", "dilbert", 0);
+			PrivateKeyAccount dilbertRewardShareAccount = new PrivateKeyAccount(repository, dilbertRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(dilbertRewardShareAccount);
+
+			// Mint enough blocks to bump testAccount levels to 9 and 10
+			final int minterBlocksNeeded = cumulativeBlocksByLevel.get(10) - 20; // 20 blocks before level 10, so that the test accounts reach the correct levels
+			for (int bc = 0; bc < minterBlocksNeeded; ++bc)
+				BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Bob self-share now comes online
+			byte[] bobRewardSharePrivateKey = AccountUtils.rewardShare(repository, "bob", "bob", 0);
+			PrivateKeyAccount bobRewardShareAccount = new PrivateKeyAccount(repository, bobRewardSharePrivateKey);
+			mintingAndOnlineAccounts.add(bobRewardShareAccount);
+
+			// Ensure that the levels are as we expect
+			assertEquals(9, (int) Common.getTestAccount(repository, "alice").getLevel());
+			assertEquals(1, (int) Common.getTestAccount(repository, "bob").getLevel());
+			assertEquals(9, (int) Common.getTestAccount(repository, "chloe").getLevel());
+			assertEquals(10, (int) Common.getTestAccount(repository, "dilbert").getLevel());
+
+			// Now that everyone is at level 7 or 8 (except Bob who has only just started minting, so is at level 1), we can capture initial balances
+			Map<String, Map<Long, Long>> initialBalances = AccountUtils.getBalances(repository, Asset.QORT, Asset.LEGACY_QORA, Asset.QORT_FROM_QORA);
+			final long aliceInitialBalance = initialBalances.get("alice").get(Asset.QORT);
+			final long bobInitialBalance = initialBalances.get("bob").get(Asset.QORT);
+			final long chloeInitialBalance = initialBalances.get("chloe").get(Asset.QORT);
+			final long dilbertInitialBalance = initialBalances.get("dilbert").get(Asset.QORT);
+
+			// Mint a block
+			final long blockReward = BlockUtils.getNextBlockReward(repository);
+			BlockMinter.mintTestingBlock(repository, mintingAndOnlineAccounts.toArray(new PrivateKeyAccount[0]));
+
+			// Ensure we are using the correct block reward value
+			assertEquals(100000000L, blockReward);
+
+			/*
+			 * Alice, Bob, Chloe, and Dilbert are 'online'.
+			 * Bob is level 1; Chloe is level 9; Dilbert is level 10.
+			 * One founder online (Alice, who is also level 9).
+			 * No legacy QORA holders.
+			 *
+			 * Chloe and Dilbert should receive equal shares of the 25% block reward for level 9 and 10
+			 * Bob should receive all of the level 1 and 2 reward (5%)
+			 * Alice should receive the remainder (70%)
+			 */
+
+			// We are after the shareBinFix feature trigger, so we expect level 9 and 10 to share the same reward (25%)
+			final int level1And2SharePercent = 5_00; // 5%
+			final int level9And10SharePercent = 25_00; // 25%
+			final long level1And2ShareAmount = (blockReward * level1And2SharePercent) / 100L / 100L;
+			final long level9And10ShareAmount = (blockReward * level9And10SharePercent) / 100L / 100L;
+			final long expectedLevel1And2Reward = level1And2ShareAmount; // The reward is given entirely to Bob
+			final long expectedLevel9And10Reward = level9And10ShareAmount / 2; // The reward is split between Chloe and Dilbert
+			final long expectedFounderReward = blockReward - level1And2ShareAmount - level9And10ShareAmount; // Alice should receive the remainder
+
+			// Validate the balances to ensure that the correct post-shareBinFix distribution is being applied
+			AccountUtils.assertBalance(repository, "alice", Asset.QORT, aliceInitialBalance+expectedFounderReward);
+			AccountUtils.assertBalance(repository, "bob", Asset.QORT, bobInitialBalance+expectedLevel1And2Reward);
+			AccountUtils.assertBalance(repository, "chloe", Asset.QORT, chloeInitialBalance+expectedLevel9And10Reward);
+			AccountUtils.assertBalance(repository, "dilbert", Asset.QORT, dilbertInitialBalance+expectedLevel9And10Reward);
+
+		}
+	}
+
+
+	private int getFlags(Repository repository, String name) throws DataException {
+		TestAccount testAccount = Common.getTestAccount(repository, name);
+		return repository.getAccountRepository().getAccount(testAccount.getAddress()).getFlags();
+	}
+
 }

src/test/resources/test-chain-v2-founder-rewards.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-leftover-reward.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-minting.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-qora-holder-extremes.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-qora-holder.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2-reward-levels.json

@@ -0,0 +1,75 @@
+{
+	"isTestChain": true,
+	"blockTimestampMargin": 500,
+	"transactionExpiryPeriod": 86400000,
+	"maxBlockSize": 2097152,
+	"maxBytesPerUnitFee": 1024,
+	"unitFee": "0.1",
+	"requireGroupForApproval": false,
+	"minAccountLevelToRewardShare": 5,
+	"maxRewardSharesPerMintingAccount": 20,
+	"founderEffectiveMintingLevel": 10,
+	"onlineAccountSignaturesMinLifetime": 3600000,
+	"onlineAccountSignaturesMaxLifetime": 86400000,
+	"rewardsByHeight": [
+		{ "height": 1, "reward": 100 },
+		{ "height": 11, "reward": 10 },
+		{ "height": 21, "reward": 1 }
+	],
+	"sharesByLevel": [
+		{ "levels": [ 1, 2 ], "share": 0.05 },
+		{ "levels": [ 3, 4 ], "share": 0.10 },
+		{ "levels": [ 5, 6 ], "share": 0.15 },
+		{ "levels": [ 7, 8 ], "share": 0.20 },
+		{ "levels": [ 9, 10 ], "share": 0.25 }
+	],
+	"qoraHoldersShare": 0.20,
+	"qoraPerQortReward": 250,
+	"blocksNeededByLevel": [ 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 ],
+	"blockTimingsByHeight": [
+		{ "height": 1, "target": 60000, "deviation": 30000, "power": 0.2 }
+	],
+	"ciyamAtSettings": {
+		"feePerStep": "0.0001",
+		"maxStepsPerRound": 500,
+		"stepsPerFunctionCall": 10,
+		"minutesPerBlock": 1
+	},
+	"featureTriggers": {
+		"messageHeight": 0,
+		"atHeight": 0,
+		"assetsTimestamp": 0,
+		"votingTimestamp": 0,
+		"arbitraryTimestamp": 0,
+		"powfixTimestamp": 0,
+		"qortalTimestamp": 0,
+		"newAssetPricingTimestamp": 0,
+		"groupApprovalTimestamp": 0,
+		"atFindNextTransactionFix": 0,
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 6,
+		"calcChainWeightTimestamp": 0
+	},
+	"genesisInfo": {
+		"version": 4,
+		"timestamp": 0,
+		"transactions": [
+			{ "type": "ISSUE_ASSET", "assetName": "QORT", "description": "QORT native coin", "data": "", "quantity": 0, "isDivisible": true, "fee": 0 },
+			{ "type": "ISSUE_ASSET", "assetName": "Legacy-QORA", "description": "Representative legacy QORA", "quantity": 0, "isDivisible": true, "data": "{}", "isUnspendable": true },
+			{ "type": "ISSUE_ASSET", "assetName": "QORT-from-QORA", "description": "QORT gained from holding legacy QORA", "quantity": 0, "isDivisible": true, "data": "{}", "isUnspendable": true },
+
+			{ "type": "GENESIS", "recipient": "QgV4s3xnzLhVBEJxcYui4u4q11yhUHsd9v", "amount": "1000000000" },
+			{ "type": "GENESIS", "recipient": "QixPbJUwsaHsVEofJdozU9zgVqkK6aYhrK", "amount": "1000000" },
+			{ "type": "GENESIS", "recipient": "QaUpHNhT3Ygx6avRiKobuLdusppR5biXjL", "amount": "1000000" },
+			{ "type": "GENESIS", "recipient": "Qci5m9k4rcwe4ruKrZZQKka4FzUUMut3er", "amount": "1000000" },
+
+			{ "type": "ACCOUNT_FLAGS", "target": "QgV4s3xnzLhVBEJxcYui4u4q11yhUHsd9v", "andMask": -1, "orMask": 1, "xorMask": 0 },
+			{ "type": "REWARD_SHARE", "minterPublicKey": "2tiMr5LTpaWCgbRvkPK8TFd7k63DyHJMMFFsz9uBf1ZP", "recipient": "QgV4s3xnzLhVBEJxcYui4u4q11yhUHsd9v", "rewardSharePublicKey": "7PpfnvLSG7y4HPh8hE7KoqAjLCkv7Ui6xw4mKAkbZtox", "sharePercent": 100 },
+
+			{ "type": "ACCOUNT_LEVEL", "target": "QgV4s3xnzLhVBEJxcYui4u4q11yhUHsd9v", "level": 1 },
+			{ "type": "ACCOUNT_LEVEL", "target": "QixPbJUwsaHsVEofJdozU9zgVqkK6aYhrK", "level": 1 },
+			{ "type": "ACCOUNT_LEVEL", "target": "QaUpHNhT3Ygx6avRiKobuLdusppR5biXjL", "level": 1 },
+			{ "type": "ACCOUNT_LEVEL", "target": "Qci5m9k4rcwe4ruKrZZQKka4FzUUMut3er", "level": 2 }
+		]
+	}
+}

src/test/resources/test-chain-v2-reward-scaling.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-chain-v2.json

@@ -46,7 +46,9 @@
 		"newAssetPricingTimestamp": 0,
 		"groupApprovalTimestamp": 0,
 		"atFindNextTransactionFix": 0,
-		"newBlockSigHeight": 999999
+		"newBlockSigHeight": 999999,
+		"shareBinFix": 999999,
+		"calcChainWeightTimestamp": 0
 	},
 	"genesisInfo": {
 		"version": 4,

src/test/resources/test-settings-v2-reward-levels.json

@@ -0,0 +1,7 @@
+{
+  "restrictedApi": false,
+  "blockchainConfig": "src/test/resources/test-chain-v2-reward-levels.json",
+  "wipeUnconfirmedOnStart": false,
+  "testNtpOffset": 0,
+  "minPeers": 0
+}

tools/block-timings.sh

@@ -0,0 +1,148 @@
+#!/usr/bin/env bash
+
+start_height=$1
+count=$2
+target=$3
+deviation=$4
+power=$5
+
+if [ -z "${start_height}" ]; then
+  echo
+  echo "Error: missing start height."
+  echo
+  echo "Usage:"
+  echo "block-timings.sh <startheight> [count] [target] [deviation] [power]"
+  echo
+  echo "startheight: a block height, preferably within the untrimmed range, to avoid data gaps"
+  echo "count: the number of blocks to request and analyse after the start height. Default: 100"
+  echo "target: the target block time in milliseconds. Originates from blockchain.json. Default: 60000"
+  echo "deviation: the allowed block time deviation in milliseconds. Originates from blockchain.json. Default: 30000"
+  echo "power: used when transforming key distance to a time offset. Originates from blockchain.json. Default: 0.2"
+  echo
+  exit
+fi
+
+count=${count:=100}
+target=${target:=60000}
+deviation=${deviation:=30000}
+power=${power:=0.2}
+
+finish_height=$((start_height + count - 1))
+height=$start_height
+
+echo "Settings:"
+echo "Target time offset: ${target}"
+echo "Deviation: ${deviation}"
+echo "Power transform: ${power}"
+echo
+
+function calculate_time_offset {
+  local key_distance_ratio=$1
+  local transformed=$( echo "" | awk "END {print ${key_distance_ratio} ^ ${power}}")
+  local time_offset=$(echo "${deviation}*2*${transformed}" | bc)
+  time_offset=${time_offset%.*}
+  echo $time_offset
+}
+
+
+function fetch_and_process_blocks {
+
+  echo "Fetching blocks from height ${start_height} to ${finish_height}..."
+  echo
+
+  total_time_offset=0
+  errors=0
+
+  while [ "${height}" -le "${finish_height}" ]; do
+    block_minting_info=$(curl -s "http://localhost:12391/blocks/byheight/${height}/mintinginfo")
+    error=$(echo "${block_minting_info}" | jq -r .error)
+    if [ "${error}" != "null" ]; then
+      echo "Error fetching minting info for block ${height}"
+      echo
+      errors=$((errors+1))
+      height=$((height+1))
+      continue;
+    fi
+
+    # Parse minting info
+    minter_level=$(echo "${block_minting_info}" | jq -r .minterLevel)
+    online_accounts_count=$(echo "${block_minting_info}" | jq -r .onlineAccountsCount)
+    key_distance_ratio=$(echo "${block_minting_info}" | jq -r .keyDistanceRatio)
+    time_delta=$(echo "${block_minting_info}" | jq -r .timeDelta)
+
+    time_offset=$(calculate_time_offset "${key_distance_ratio}")
+    block_time=$((target-deviation+time_offset))
+
+    echo "=== BLOCK ${height} ==="
+    echo "Minter level: ${minter_level}"
+    echo "Online accounts: ${online_accounts_count}"
+    echo "Key distance ratio: ${key_distance_ratio}"
+    echo "Time offset: ${time_offset}"
+    echo "Block time (real): ${time_delta}"
+    echo "Block time (calculated): ${block_time}"
+
+    if [ "${time_delta}" -ne "${block_time}" ]; then
+      echo "WARNING: Block time mismatch. This is to be expected when using custom settings."
+    fi
+    echo
+
+    total_time_offset=$((total_time_offset+block_time))
+
+    height=$((height+1))
+  done
+
+  adjusted_count=$((count-errors))
+  if [ "${adjusted_count}" -eq 0 ]; then
+    echo "No blocks were retrieved."
+    echo
+    exit;
+  fi
+
+  mean_time_offset=$((total_time_offset/adjusted_count))
+  time_offset_diff=$((mean_time_offset-target))
+
+  echo "==================="
+  echo "===== SUMMARY ====="
+  echo "==================="
+  echo "Total blocks retrieved: ${adjusted_count}"
+  echo "Total blocks failed: ${errors}"
+  echo "Mean time offset: ${mean_time_offset}ms"
+  echo "Target time offset: ${target}ms"
+  echo "Difference from target: ${time_offset_diff}ms"
+  echo
+
+}
+
+function estimate_key_distance_ratio_for_level {
+  local level=$1
+  local example_key_distance="0.5"
+  echo "(${example_key_distance}/${level})"
+}
+
+function estimate_block_timestamps {
+  min_block_time=9999999
+  max_block_time=0
+
+  echo "===== BLOCK TIME ESTIMATES ====="
+
+  for level in {1..10}; do
+    example_key_distance_ratio=$(estimate_key_distance_ratio_for_level "${level}")
+    time_offset=$(calculate_time_offset "${example_key_distance_ratio}")
+    block_time=$((target-deviation+time_offset))
+
+    if [ "${block_time}" -gt "${max_block_time}" ]; then
+      max_block_time=${block_time}
+    fi
+    if [ "${block_time}" -lt "${min_block_time}" ]; then
+      min_block_time=${block_time}
+    fi
+
+    echo "Level: ${level}, time offset: ${time_offset}, block time: ${block_time}"
+  done
+  block_time_range=$((max_block_time-min_block_time))
+  echo "Range: ${block_time_range}"
+  echo
+}
+
+fetch_and_process_blocks
+estimate_block_timestamps